Maech 29, 1907] 



SCIENCE 



483 



such a procedure may even lead to a great- 

 er efficiency of the mechanism. Professor 

 Irving Fisher tells us recently that nine 

 Yale students under the influence of pro- 

 longed mastication of a diet greatly re- 

 duced in proteid and in caloric values, 

 gained very much in endurance in per- 

 forming certain physical tests. 



Is there, indeed, a difference between 

 the economies of human-made organiza- 

 tions and those of the living organism? 

 I have stated above that the factors of 

 safety in mechanical constructions are 

 after all only factors of ignorance. Pos- 

 sibly wise nature constructs her organisms 

 on such an efficient principle which permits 

 the accomplishment of the greatest amount 

 of work on a minimum supply of material 

 and energy. It would be a fascinating 

 distinction between a dead mechanism and 

 a living organism — if true. 



The subject of this lecture will be an 

 investigation of this question, an investiga- 

 tion whether the structures and functions 

 of the animal organism are constructed 

 with a special consideration for the great- 

 est economy or for the greatest safety. Or 

 to leave the purposefulness of the organiza- 

 tion out of discussion, I may perhaps put 

 it more correctly by saying that it will be 

 essentially an investigation into the ratios 

 of the supply of material in many organs 

 of the body to the amount of work they 

 are expected to perform. I believe that 

 the investigation may lead to some in- 

 structive general conclusions of a theoret- 

 ical and practical character. As already 

 stated, the problem seems to me to be new 

 and, as far as I know, no original investiga- 

 tions were carried out with the special pur- 

 pose of solving it. There are, however, a 

 great many well-established facts brought 

 out in theoretical and practical work un- 

 dertaken for other purposes, which are, 

 nevertheless, capable of throwing a good 



deal of light upon our problem. Such 

 facts have the advantage of being unbiased 

 witnesses, since no preconceived theory was 

 at the bottom of their discovery. My task 

 will consist in reviewing these facts as far 

 as they are available, or more correctly, as 

 far as they are known to me, and bringing 

 them impartially in proper relation to our 

 problem. 



I shall commence with the plain tissues 

 of the body. In the multitude of studies 

 on these tissues there are not many inves- 

 tigations which could be utilized for our 

 purpose. However, a series of careful in- 

 vestigations, recently published by Triepel, 

 have an intimate bearing on our problem. 

 Triepel investigated the elasticity and re- 

 sistance of several tissues, like muscle, ten- 

 don, elastic tissue, bone, cartilage, etc. For 

 us the following statements are of special 

 interest. For muscle, tendon and elastic 

 tissue Triepel found that the maximum 

 stretching which may occur in the animal 

 body is not far below that degree which 

 can cause tearing of these tissues. The 

 resistance of bones and cartilages to a 

 crushing stress is, however, far above any 

 stress which might occur in normal life. 

 With regard to muscle, tendon and elastic 

 tissue it appears, therefore, that the struc- 

 tures in themselves have practically no 

 factors of safety above the maximum stress 

 to which they might be subjected. Any 

 unexpected tension above the maximum 

 occurring in ordinary life might lead to a 

 rupture of these tissues. Triepel, however, 

 calls attention to the fact that the degree 

 of stretching of these tissues is greatly 

 limited by their connections with the struc- 

 tures surrounding them, especially by the 

 skeletal parts. These limitations will for 

 the most part prevent these tissues from 

 reaching their breaking point. We may 

 then say that muscle, tendon and elastic 

 tissues have no factors of safety in the 



