584 Mast, Loeb's Mechanistic Conception of Life. 



somes. These facts, admittedly of great importance, or any other 

 facts that have heen established in regard to the sperm, do not 

 appear to me to warrant Loeb's conclusions stated above. Prac- 

 tically nothing regarding the chemical changes in the egg preceding 

 and accompanying activation is known. How then can it be main- 

 tained, except in the most superficial sense, that this process has 

 been practically completely reduced to physico-chemical principles? 

 The same is true with reference to heredity. The establishment of 

 the fact that heritable characteristics are associated with chromo- 

 somes does, indeed, mark a great advance in the study 01 inher- 

 itance. But the statement that this whole problem is practically 

 solved and that we may hope that all the riddles still connected 

 with it as well as all those connected with all other biological 

 phenomena will disappear in rapid succession, must be looked upon 

 largely as the personal opinion of an enthusiast. Many riddles 

 will undoubtedly disappear but some bid fair to stay with us, for 

 example certain features concerning the association of hereditary 

 characters with chromosomes and specific changes within them. 

 Even if we succeed in discovering every chemical and every physical 

 change in every chromosome and precisely how each character is 

 connected with them - - and we shall no doubt be able to do much 

 along this line of the greatest value both practical and theoretical - 

 there still remains the riddle as to why they are thus associated. 

 This riddle and others of a similar sort are clearly beyond mechanics, 

 even in the loose sense in which Loeb has used this term, for 

 they involve not only the question of order in nature but also the 

 question of why there is order. What hope is there then in our 

 author's "mechanistic conception" for the solution of such problems. 



It is however in the fields of morphogenesis and behavior that 

 anti-mechanists have found the most fertile source of material for 

 their arguments. And it is therefore not surprising to find these 

 subjects rather extensively treated by our author. 



He discusses morphogenesis in two different sections and 

 appears to arrive at quite different conclusions as to an explanation 

 of this phenomenon. 



He found experimentally, that the place of origin and the 

 direction of growth in a number of organisms is dependent upon 

 gravity and contact. And he concludes (p. 91): "The circumstances 

 that determine the forms of animals and plants are only the dif* 

 ferent forms of energy, in the sense in which this word is used 

 by the physicist, and have nothing to do with natural selection." 

 In this same section he maintains (p. 108) that the reason why the 

 egg of the sea-urchin normally gives rise to only one embryo "is 

 due simply to the geometrical shape of the protoplasm, which, 

 under normal conditions, is that of a sphere" (in other words 



