MILLARD, J.
(Pro Tempore)
This is an appeal from a judgment of the Circuit Court of Multnomah County for $39,552.05 and $84.41 costs and disbursements pursuant to a verdict in favor of plaintiff, rendered in an action based upon alleged common-law negligence and upon negligence resulting from an alleged violation of the Employers’ Liability Act, all having to do with an alleged employer- employee relationship and wherein plaintiff claimed damages arising out of personal injury.
As and for its first assignment defendant attempts to demur to plaintiff’s amended complaint on the ground that such complaint does not state facts suffi[3]*3cient to constitute a cause of action. The complaint, after alleging the corporate capacity of defendant, states that the said defendant employed plaintiff in the capacity of elevator operator in the Central Building in Portland, Oregon; that on October 6, 1954 plaintiff was upon an elevator in said building, preparing to depart from the basement, when the elevator was caused to be suddenly started while plaintiff was partly standing on a 14-inch ledge adjacent to the elevator, causing her to be thrown into the elevator shaft approximately six feet deep, and injured. Plaintiff charges various specifications of negligence. These have to do with suddenly starting the elevator without ascertaining the location and position of plaintiff; failure to stop or to control after suddenly starting; failure to warn, and in failing and neglecting to construct or alter the elevator doors so that the same were in close proximity to said elevator and the shaft thereof inclosed. An additional specification charges defendant with negligence
“In failing and neglecting to use every care, device and precaution practicable to have been used in that said defendant could have ascertained the location and position of this plaintiff before suddenly starting said elevator, could have stopped or properly controlled said elevator after starting same, could have warned plaintiff of intention to start said elevator, and could have so constructed and arranged the doors so that they were in close proximity to the edge of the elevator, inclosing the shaft thereof, which precautions and devices would not have impaired the efficiency of said electrically operated elevator or the operation thereof.”
As a result plaintiff alleges she received injuries to her back, chest, ribs, left arm and hand, fracture of her spine, ribs, sternum, to her damage in the sum [4]*4of $50,000. Plaintiff also alleges special damages by way of doctor, hospital expenses and loss of wages.
In support of its contention that the amended complaint does not state a cause of action, defendant argues that, in part, plaintiff is attempting to proceed under the Employers’ Liability Law and particularly under OPS 654.305, commonly referred to as the “and generally clause” and which reads as follows:
“Generally, all owners, contractors or subcontractors and other persons having charge of, or responsible for, any work involving a risk or danger to the employes or the public, shall use every device, care and precaution which it is practicable to use for the protection and safety of life and limb, limited only by the necessity for preserving the efficiency of the structure, machine or other apparatus or device, and without regard to the additional cost of suitable material or safety appliance and devices.”
In maldng this contention defendant has reference to that specification of negligence which charges defendant with “failing and neglecting to use every care, device and precaution to have been used” in the particulars hereinbefore set forth. In the first place, defendant misconceives the theory of plaintiff’s complaint. A careful reading discloses that it not only proceeds on the theory of a violation of the Employers’ Liability Act but also on the theory of common-law negligence, i.e., the duty of an employer to furnish his employee a safe place to work. A complaint alleging several specifications of negligence is sustainable as against a demurrer, if the complaint- is sufficient as to any one of them. Hough v. Grants Pass Power Co., 41 Or 531, 69 P 655. Since the specifications having to do with the common-law duty are so clearly suffi[5]*5cient, it follows that the ground of the demurrer cannot be sustained.
But, even though the complaint contained only the specification of negligence which defendant claims is objectionable, the grounds of the demurrer asserted here for the first time cannot be sustained. Defendant says there is no allegation that the defendant was either the owner, contractor or other person in charge of, or responsible for any work involving a risk or danger to the employees, and that under ORS 654.305, above set forth, such allegation is necessary. In the first place, it is alleged that defendant employed plaintiff in the capacity of elevator operator in the Central Building and that she was in an elevator in said building at the time of the accident,-and that defendant was negligent in not inclosing the shaft, etc. "While the complaint leaves something to be desired in such statement, it must also be kept in mind that a demurrer was not interposed in the court below nor was it subjected to motion to strike or to make more definite and certain. Further, at the trial it clearly appeared that the defendant was in charge of the building. Upon appeal, a complaint not demurred to or moved against in the trial court, every reasonable inference is resolved in support thereof. Sterrett v. Hurlburt et al, 129 Or 520, 522, 275 P 689, 278 P 986. Under the circumstances it appears therefore that the complaint is sufficient at this stage of the proceeding and further that defendant was not thereby misled. But even so, defendant says, in effect,, that since the complaint does not specifically allege that the work involved risk and danger, the questioned specification is bad en to to. We agree with defendant’s legal contention to the effect that under the Employers’ Liability Act it is necessary that the com[6]*6plaint show that the work involved risk or danger. In this connection attention is called to OES 654.310 which is a part of the Employers’ Liability Law and which is entitled “Protective measures to be observed regarding certain machines, equipment and devices which are dangerous to employes.” The statute provides, in part, that any person engaged in the use of any dangerous appliance or in the operation of any machinery shall see. that “All shafts, wells, floor openings and similar places of danger are inclosed.” An elevator is machinery within the definition of the statute. Thompson v. Union Fishermen’s Co-op. Packing Co., 118 Or 436, 235 P 694, 246 P 733; Poole v. Tilford, 99 Or 585, 195 P 1114.
While again, the complaint leaves something to be desired, we are of the opinion that, in view of the statutory provisions, and in the absence of any demurrer or motion in the trial court, the complaint is sufficient and that it does appear that the work involved risk and danger to the employee.
In Rorvik v. North Pac. Dumber Co., 99 Or 58, 190 P 331, 195 P 163, where liability was predicated under the Employer’s Liability Act, and where plaintiff did not allege that the work in which plaintiff’s decedent was employed, involved risk and danger but did allege the circumstances, it was held that the complaint was sufficient on appeal where no demurrer or motion was interposed before the appeal.
The next assignment claims error on the part of the trial court in striking defendant’s supplemental answer and challenge to plaintiff’s complaint. This supplemental answer and challenge attempted to evoke the protection of the Workmen’s Compensation Act. After the court granted a motion to strike said supplemental answer and challenge, the plaintiff filed [7]*7an amended complaint which was the complaint used in the trial. "Where an amended complaint is filed, the original complaint ceases to be a part of the pleading. Mumper v. Matthes, 186 Or 357, 364, 206 P2d 86. Since the amended complaint superseded the original complaint, the error, if any, is of no consequence, and hence there is no merit in this contention.
Defendant’s next assignment of error has to do with the action of the court below in striking the supplemental answer and challenge and plea in abatement filed by defendant to the amended complaint. The assignment fails to mention that there are in fact three supplemental answers and challenges, nor does it set forth in such assignment plaintiff’s motion to strike, the allowance thereof being claimed as' error, all in contravention of Rule 16 of this Court. We would be thereby justified in refusing to review the assignment. See Scheufele v. Newman, 187 Or 263, 210 P2d 573. However, the assignment does refer to page 2 of the bill of exceptions from which we learn that there were three supplemental answer and challenges, as well as a so-called plea in abatement, all of which are set forth in the abstract.
Defendant in his first supplemental answer and challenge alleges, in effect, that the plaintiff was an employee of the estate of Rose White, deceased, who owned and operated the Central Building, and that said employer was engaged in a hazardous occupation as defined by the Workmen’s Compensation Law in the operation of said building, and that “both the plaintiff and her employer were subject to said law.” The answer further alleges that the defendant was the managing agent of the Estate of Rose White in operating the building. Defendant further alleges that subsequent to her injuries plaintiff filed a claim with [8]*8the State Industrial Accident Commission for compensation for her injuries and proceedings were had on such claim, resulting in payment to plaintiff by said Commission of the benefits to which she was entitled. Defendant further alleges that at the time plaintiff “received her injuries, she was a workman subject to the Compensation Law and was employed by an employer subject to said law, and she was on premises owned and operated by her employer, namely, the Estate of Eose White, deceased, by reason whereof the plaintiff is exclusively confined to her claim under the Workmen’s Compensation Law in lieu of any and all claims against the defendant arising out of the accident or because of any injury or disability therefrom.”
In the second supplemental answer and challenge defendant sets up the same allegation of the first supplemental answer just referred to with reference to the fact of employment by the Estate of Eose White, deceased, in the operation of the Central Building, and with reference to the claim filed with the State Industrial Accident Commission and the further proceedings thereonj and then further alleges that “Plaintiff did -not elect to prosecute a-third party action against the defendant as required by the Workmen’s Compensation Law and in so failing, the plaintiff has no right to prosecute the present action and has no right to recover.”
In the third supplemental answer and challenge defendant makes the same allegation as in the second supplemental answer and challenge except with reference to a third party action, as quoted just above, and in lieu thereof, alleges “that the elevator described in the amended complaint was located upon and as a part of the premises owned and maintained by the [9]*9Estate of Eose White, deceased, known as the Central Building, and at the time of her accident the plaintiff was on the premises of her employer and was engaged in her employment and was not at any time away from the plant of her employer.”
The plea in abatement heretofore mentioned, after alleging the corporate capacity of defendant, further alleges that said defendant was the managing agent of the Central Building, the property of the Estate of Eose White, deceased, and that plaintiff, while employed as an elevator operator thereon received injuries and thereafter applied for and received benefits and payments from the State Industrial Accident Commission, and “that by reason of applying for and receiving said benefits by the plaintiff, the State Industrial Accident Commission is subrogated to the rights of claim of the plaintiff, if any.”
To these various supplemental answers and challenges, as well as the plea in abatement, plaintiff filed a motion to strike on the ground that answers and plea were sham, frivolous, irrelevant and immaterial and did not constitute a defense or as to the plea, á matter in abatement. Both of these motions were allowed by the court, the Honorable James E. Bain presiding, and these various pleadings were stricken on the ground that the complaint tendered the issue as to whether or not plaintiff was an employee of defendant.
“(1) Every workman subject to OES 656.002 to 656.590 while employed by an employer subject to OES 656.002 to 656.590 who, while so employed, sustains an accidental injury, or accidental injury to prosthetic appliances arising out of and in the course of his employment and resulting in his disability, or the beneficiaries of such workman, if the injury results in death, are entitled to receive [10]*10from the Industrial Accident Fund the sums specified in ORS 656.002 to 656.590. The repair or replacement of prosthetic appliances so injured shall be provided subject to the approval of the commission.
“(2) The right to receive such sums is in lieu of all claims against his employer on account of such injury or death, except as otherwise specifically provided in ORS 656.002 to 656.590.” ORS 656.152.
In construing this statute with reference to the protection afforded the employer under the Workmen’s Compensation Act, it has been held, as follows:
“An injured workman cannot have both an award of compensation and an action for damages against a purported tort feasor except in the specific instances mentioned in the act. In all cases, except the rare exceptions set forth in the act, compensation, and that alone, is the measure of recovery. Compensation, unless an exception, is the exclusive remedy. * * *” Kowcun v. Bybee, 182 Or 271, 296, 186 P2d 790.
It might be argued that Kowcun v. Bybee, supra, does not here apply, on the theory that it is not shown that plaintiff was employed by an employer subject to the Workmen’s Compensation Act. We hold that if it be true that plaintiff has applied for and received benefits under the Act, it is now too late to raise that question unless she can, on some theory of mistake, return the benefits she has received and cause the record before the Accident Commission to be expunged. The reason therefore lies in the fact that not only is the State Industrial Accident Commission a quasi-judicial tribunal created by the Legislature, with exclusive jurisdiction, subject to judicial review, to determine the question of who is entitled to an allowance of compensation as an employee of an employer [11]*11subject to the act, but that the remedy provided therein is exclusive. That such is the case clearly appears from the statutes involved and our prior decisions.
A judicial tribunal may be defined as a legal body given power to decide upon the legality of claims and construe and apply the law and define the rights of parties with reference to transactions already had. See, In re Commissioners of Counties Comprising Seventh Judicial District, 22 Okl 435, 98 P 557, 559; Merrill v. Sherburne, 1 NH 204, 8 Am Dee 52. See, also, Isbill v. Stovall (Tex Civ App) 92 SW2d 1067, 1070; Black’s Law Dictionary, 4th Ed 986 (defining judicial power).
That the State Industrial Accident Commission in the allowance of claims for compensation is so regarded appears in Chebot v. State Industrial Acc. Com., 106 Or 660, 669, 212 P 792, wherein this court in discussing the right to appeal refers to the Commission as a “tribunal.” Further, ORS 656.282 provides, in part, that “The Commission may hear and determine all questions within its jurisdiction.” We assume that it will not be necessary to cite authority to the effect that the Commission not only has the power, but the duty, to determine in the first instance, the right to compensation. ORS 656.290 which may be referred to as the appeal section of the Workmen’s Compensation Act provides, in part, that “(1) If the court determines that the commission has acted within its power and has correctly construed the law and facts, the decision of the commission shall be confirmed; * * In other words, the Legislature has delegated to the Commission the sole power to decide, subject to judicial review.
In Chebot v. State Industrial Acc. Com., supra, it was stated, at page 670, that the act was “plainly [12]*12intended to effect a withdrawal from interference by the courts of all questions relating to compensation to employees injured in hazardous employments, so far as that result is practicable or attainable, in view of the absolute right of the individual to invoke the power and jurisdiction of the courts to prevent rank injustice or the denial of substantial legal rights.” At pages 666 and 667 of the same case it was stated that “The statute gives the commission general jurisdiction over the Industrial Accident Fund and over the employers and employees contributing thereto, and special jurisdiction over the particular case of an injured workman when such workman filed with the commission his application for compensation.” That such jurisdiction was to be deemed exclusive clearly appears from the purpose for which the legislation was enacted. “The purpose in adopting the Oregon compensation law was to protect the employer as well as the employee and his beneficiaries, and to avoid the expense and delay incident to litigation.” Bigby v. Pelican Bay Lbr. Co., 173 Or 682, 692, 147 P2d 199. In the case last cited it was also held, at page 692, that “The rights and remedies provided by the workmen’s compensation act are exclusive.” To the same effect, see Kowcun v. Bybee, supra; Ellis v. Fallert, 209 Or 406, 412, 413, 307 P2d 283; Hall v. Copco Pacific, Ltd., 224 F2d 884, 886.
It is to be noted that ORS 656.152(2) expressly provides that “The right to receive such sums is in lieu of all claims against his employer on account of such injury or death, * * We hold this to mean any employer, in view of the purposes of the Act and the exclusive jurisdiction given the Commission. The statute does not say “in lieu of compensation”, or “in lieu of a cause of action”, but, “in lieu of all claims,” [13]*13as was pointed out in Ellis v. Fallert, supra, at page 412. See, Article entitled “Bes Judicata as Begards Decisions or Awards Under Workmen’s Compensation Acts”, 122 ALR 550, at pages 594 and 595, and cases there cited. We think the decisions there noted are to the effect that once the finding as to employer and employee relationship is made by the tribunal intrusted with that duty, the decision is final and conclusive until set aside.
If it be true that plaintiff is accepting compensation from the State Industrial Accident Fund through contributions to the fund made in her behalf by the Estate of Bose White, then the situation here would be analogous to one where plaintiff having sued the Estate of Bose White on the theory of employer-employee relationship, and having recovered a small amount and being dissatisfied therewith, and without making restitution or expunging the record, sues another person for the same injury on account of an employer-employee relationship in an attempt to recover twice for the same injury, thus effecting a double recovery. This is the very thing the court abhorred in Matheny v. Edwards Ice Machine & Supply Co., 39 F2d 70. We therefore hold that under proper allegations defendant is entitled to raise the defense of the protection afforded by the Workmen’s Compensation Act, as provided by OBS 656.152(2). Further, to hold otherwise we would, in effect, presume that the Commission had not properly performed its function, when the presumption is the other way, that is, that official duty was regularly performed and hence compensation was allowed to one entitled thereto. We wish to further point out that this construction is consistent with the general statutory plan relating to provisions of the Workmen’s Compensation [14]*14Act. Plaintiff may still bring her action if she comes within one of the statutory exceptions. Where a Servant has taken advantage of the Workmen’s Compensation Law he cannot recover of his employer unless he brings himself within one of the exceptions mentioned in the Act. Jenkins v. Carman Mfg. Co., 79 Or 448, 451, 155 P 703. To hold otherwise could only lead to confusion, in view of our earlier holdings, and a return to the courts of that jurisdiction previously denied them. It should be pointed out that the defendant at the trial offered in evidence (not received) an original file showing that the plaintiff has actually appealed to the circuit court from an award of the State Industrial Accident Commission, being dissatisfied with the benefits accorded her.
It should be further pointed out that the construction here adopted is in accordance with the constitutional requirement of equal protection of the laws in that it is required that a law shall affect alike all persons in the same class and under similar conditions. In this case, the construction adopted treats alike all persons who have accepted the benefits of the Workmen’s Compensation Act. It would indeed be an anomalous situation that would allow one person, who has accepted the benefits of the Act, to sue his employer on some theory other than the exceptions enumerated in the Act and deny the same privilege to the great majority who accept such benefits.
In view of the law, as above stated, defendant is apparently attempting by its several supplemental answers and challenges and plea in abatement to evoke the protection of the Workmen’s Compensation Law for and on behalf of defendant. Defendant argues that such supplemental answers and challenges are [15]*15permissible under OES 656.154 and OES 656.324, the pertinent portions of which read as follows:
“(1) If the injury to a workman is due to the negligence or wrong of a third person not in the same employ, the injured workman, or if death results from the injury, his widow, children or other dependents, as the case may be, may elect to seek a remedy against such third person. However, no action shall be brought against any such third person if he or his workman causing the injury was, at the time of the injury, on premises over which he had joint supervision and control with the employer of the injured workman and was an employer subject to OES 656.002 to 656.590.
“(2) As used in this section, ‘premises’ means the place where the employer, or his workman causing the injury, and the employer of the injured workman, are engaged in the furtherance of a common enterprise or the accomplishment of the same or related purposes in operation.” OES 656.154.
“A challenge of the right to bring such third party action shall be made by supplemental pleadings only and such challenges shall be determined by the court as a matter of law.” OES 656.324(3).
In Kowcun v. Bybee, supra, 182 Or 271, 285, the words “third person” as used in the Workmen’s Compensation Law, were defined as “a third person not in the same employ.”
See also, Plummer v. Donald M. Drake Co., 212 Or 430, 438, 320 P2d 245; Bigby v. Pelican Bay Lumber Co., 173 Or 682, 147 P2d 199; King v. Union Oil Co., 144 Or 655, 24 P2d 345; Matheny v. Edwards Ice Machine & Supply Co., 39 F2d 70. Since the first supplemental answer and challenge alleges that defendant was the managing agent of the Central Building of and for the Estate of Eose White, it follows that both plaintiff and defendant were in the same [16]*16employ and hence under the definition given, defendant could not be a third party; and therefore was not entitled to the challenge so prescribed by statute. Further, since the amended complaint directly alleges defendant was the employer of the plaintiff, it follows that a third party action was not involved in any event, and hence all three of the challenges are insufficient as challenges under ORS 656.324.
Since each of these so-called pleadings were entitled supplemental answers and challenges and since they cannot be sustained as challenges, can they be sustained as answers? “It is a general rule that the character of a pleading is to be determined, not from the title given it but from its allegations.” 1 Bancroft Code, Pleading, Section 7, page 19. See, also, Wright v. Morton et al, 125 Or 563, 569, 267 P 818; Smith v. Martin, 94 Or 132, 140, 185 P 236; Saylor v. Commonwealth Banking Co., 38 Or 204, 62 P 652. Further than that, since these pleadings were entitled answers as well as challenges, it appears that the defendant’s theory also encompassed such pleadings as answers. They were also so treated by the plaintiff, since one of the grounds of the motion to strike was based on the contention that they did not state a defense. This court therefore concludes that it may also consider such pleadings as answers.
Does the first supplemental answer submit a defense? Some of the allegations do not. For example, in each of the said answers it is alleged “that both the plaintiff and her employer were subject to said law,” the word “law” having reference to the Workmen’s Compensation Law.
In Coblentz v. State Ind. Ago. Com., 203 Or 258, 262, 279 P2d 503, it was alleged that the plaintiff “was not subject to the Workmen’s- Compensation [17]*17Law of California” and such allegation was held to be a conclusion of law and “the ultimate question for determination by the court * * * based upon facts well pleaded and proved.” The same reasoning applies to the questioned allegations in this ease. A conclusion of law in a pleading is not issuable, requires no denial, does not aid the pleading and amounts to a nullity. Kelley v. Mallory, 202 Or 690, 697, 277 P2d 767. The same reasoning applies to the allegation, “said employer was engaged in a hazardous occupation as defined by the Workmen’s Compensation Law.” As a matter of fact, we are of the opinion that the work was not classified as hazardous under the statute. See OES 656.084. Nor has it been declared hazardous by the Commission by virtue of OES 656.086.
From the first answer, stripped of its nonessentials and aided by the amended complaint, it appears that plaintiff was an employee of the Estate of Eose White, deceased, in the operation of the Central Building, and that at the time mentioned in the complaint, defendant was the managing agent for the estate in the operation and management of said building, and that plaintiff filed her claim for her injuries with the State Industrial Accident Commission and received benefits. We already know from the complaint that the accident happened in the Central Building and there is enough to indicate it was the same accident to which both pleadings refer. Defendant fails to show by its pleading that the Estate of Eose White made its contribution to the State Industrial Accident Fund and that it was on that basis plaintiff was making her claim. While the pleading, therefore, was deficient, at least in that respect it did contain some elements pf a defense. A motion to strike cannot take the place of a demurrer. Murphy v. Oregon Engraving Co., [18]*1894 Or 534, 186 P 12. Since the pleading contains some elements of a defense, the motion to strike was improperly allowed.
Since plaintiff is alleged to have accepted the benefits of the Workmen’s Compensation Law, under the doctrine of Kowcun v. Bybee, supra, referred to above, she is concluded, unless she can show a cause of action under one of the exceptions to the act set forth in ORS 656.312, hereinafter quoted:
“If a workman of an employer engaged in a hazardous occupation in violation of ORS 656.052, or of an employer in default, as provided in ORS 656.560, receives an accidental injury in the course of his employment, or if a workman receives an accidental injury due to the negligence or wrong of a third person, entitling him under ORS 656.154 to seek a remedy against such third person, such workman or, if death results from the injury, the other beneficiaries shall elect whether to recover damages from such employer or third person. If a workman leaves beneficiaries who are minors, the right of election shall be exercised by their surviving parent, if any; otherwise, such election shall be exercised by the guardian.” ORS 656.312.
We have already held under the allegations of the answer that defendant is not a third party and that the occupation is not hazardous. Does it appear that defendant is an employer in default as provided in ORS 656.560? Obviously not, since no default is alleged.
With relation to third parties, ORS 656.324(2) provides that “In any third party action brought pursuant to ORS 656.002 to 656.590, the fact that the injured workman or his beneficiaries are entitled to or have received benefits under ORS 656.002 to 656.590 shall not b¡e pleaded or admissible in evidence.”
[19]*19There is no such provision with relation to defaulting employers. Therefore plaintiff, since she is proceeding against an employer, unless she denies having received benefits, must now allege and show that she comes under one of the exceptions of ORS 656.312 and in this instance, that the defendant was a defaulting employer. Under the conclusion reached, it appears, and we hold, that the court was in error in striking the first answer.
Since it is not contended by plaintiff that defendant was a third party, the second answer was not responsive and hence was properly stricken. Further, the matter of election of remedies is not involved here, since plaintiff, if she accepted the benefits of the Workmen’s Compensation Law, was without any other remedy unless she can show that the defendant was a defaulting employer.
With reference to the plea in abatement, defendant argues that by virtue of ORS 656.314 the State Industrial Accident Commission should have been joined as a party plaintiff and the action abated until that was done, since that statute provides that the Commission has a lien in the amount of the compensation paid to the workman under the provisions of the Workmen’s Compensation Law of this state. An examination of the statute, in the light of companion statutes, discloses that it deals with actions by a workman against a third party, a delinquent employer or a non-participating joint employer. We have already held that a third party action or an action against a defaulting employer is not here so far involved. The plea makes no allegation with reference to a non-participating joint employer or a delinquent employer, and hence the plea was properly stricken.
In view of the conclusions reached, it becomes un[20]*20necessary to discuss the remaining assignments of error. Since defendant was deprived of a defense, the case must be reversed and remanded with directions to reinstate the first answer except with regard to the conclusions of law stated therein which should be stricken.