74 



SCIENCE 



[N. S. Vol. XLV. No. 1152 



in the offspring. Such arguments were 

 very common in biology before the experi- 

 mental method was recognized as necessary 

 to test the validity of our assumptions. 

 Since experimental tests were made we 

 have learned that eyes do not degenerate 

 when animals are kept in the dark. Thus 

 Payne raised sixty-nine successive genera- 

 tions of Drosophila in the dark without 

 noticing any trace of degeneracy in the eye 

 or its function. Uhlenhuth found that eyes 

 when transplanted into the back of sala- 

 manders will (after a transitory degenera- 

 tion) regenerate completely, and remain 

 normal no matter whether the animals are 

 kept in the dark or in the light. Hereditary 

 blindness (e. g., hereditary glaucoma in 

 man) is apparently due to a mutation 

 (probably a chemical change in one chromo- 

 some) which originates, as far as our pres- 

 ent facts show, independently of use or dis- 

 use of the eye. We know through Morgan's 

 observations that insects with mutilated or 

 rudimentary wings may arise suddenly as 

 mutations from parents which used their 

 wings. Lack of the practise of flying does 

 according to our present knowledge no more 

 lead to the hereditary disappearance of 

 wings than darkness leads to hereditary 

 degeneration of the eyes. The statement, 

 that a nation by not going to war will lose 

 any of its inherited "virile virtues" is not 

 supported by our present biological knowl- 

 edge. 



3. The biology of which the war enthu- 

 siasts make use is essentially antiquated, 

 and so we need not be surprised to find that 

 they consider war to be based on what they 

 call the "biological law of nature," the 

 "struggle for existence," or the "survival 

 of the fittest." Such ideas are expressed 

 by war enthusiasts in America as well as 

 in Europe and we may be permitted to 

 make the following quotation without giv- 

 ing the name of its author. 



The struggle for existence is in the life of na- 

 ture the basis of all healthy development. All ex- 

 isting things show themselves to be the result of 

 contesting forces. So in the life of man the 

 struggle is not merely the destructive but the life- 

 giving principle. . . . The law of the stronger holds 

 good everywhere. Those forms survive which are 

 able to procure for themselves the most favorable 

 conditions of life and to assert themselves in the 

 universal economy of nature. The weaker suc- 

 cumb. This struggle is regulated and restrained 

 by the unconscious sway of biological laws and by 

 the interplay of opposite forces. In the plant 

 world and the animal world this process is worked 

 out in unconscious tragedy. . In the human race it 

 is consciously carried out, and regulated by social 

 ordinances. The man of strong wiU and strong 

 intellect tries by every means to assert himself, 

 . . . and in this effort the individual is far from 

 being guided merely by the consciousness of right. 

 . . . The nation is made up of individuals. . . . 

 The motive which influences each member is promi- 

 nent in the whole body. It is a persistent struggle 

 for possessions . . . and right is respected so far 

 only as it is compatible with advantage. 



The "struggle for existence" and the 

 "survival of the fittest" are no "laws of 

 nature ' ' in the sense in which the term law 

 is used in the exact sciences. We speak of 

 a law of nature when we are able to ex- 

 press a phenomenon as a mathematical 

 function of its variables. We thus speak 

 of a law of gravitation, of Ohm's law, or 

 in biology ot Mendel's law of segregation. 

 As long as biologists did not realize that 

 their statements needed not only a quali- 

 tative experimental test but also a quanti- 

 tative verification they talked in a loose 

 way, and this did not change until the 

 methods of physics and physical chemistry 

 began to invade biological research. The 

 progress made by Mendel lay in this, that 

 he introduced the quantitative method of 

 the physicist into the investigations of 

 hybridization and he was ignored because 

 the zoologists and botanists of his time did 

 not grasp the fact that the progress of sci- 

 ence depends upon the invention or appli- 

 cation of such methods. 



