Mast, Loeb's Mechanistic Conception of Life. 583 



than a statement that nature is orderly and that an explanation of 

 any phenomenon consists merely in ascertaining the position of the 

 phenomenon in the whole series of natural events, that is, in ascer- 

 taining the order of events in nature. Probably nearly every one 

 would, at least in a limited sense, accept this as a definition of an 

 explanation, but very few indeed would follow our author in the 

 implied assertion that such an explanation is necessarily physico- 

 chemical or mechanical. It thus appears that these terms have 

 been used in a very loose sense, in my opinion a wholly un- 

 justifiable sense; and much of the controversy regarding Loeb's 

 apparent dogmatic ultra mechanistic tendencies center in this un- 

 fortunate circumstance. Not only is mechanism used synonymously 

 with physico-chemism, it is also used synonymously with deter- 

 minism. 



If however such a definition of mechanism be accepted some of 

 Loeb's conclusions necessarily follow, but others appear, even on 

 this basis, to be without foundation. Some of these I wish to 

 consider now. In selecting only questionable matter for treatment 

 in our review it should be emphasised that it is taken for granted 

 that the author's splendid achievement in certain fields is generally 

 recognized, and that limitations of space prevent the consideration 

 of much in which the reviewer would be in agreement with the 

 author. 



Loeb maintains that the function of the sperm is twofold. It 

 causes the egg to develop and it serves to transmit male charac- 

 ters. Both of these phenomena, our author holds, have already 

 been largely reduced to physico-chemical principles. He says (p. 20): 

 "The problem of sex determination has, therefore, found a simple 

 solution, and simultaneously Mendel's law of segregation also finds 

 its solution." and (p. 14) "The process of the activation of the egg- 

 by the spermatozoon, which twelve years ago was shrouded in 

 complete darkness, is today practically completely reduced to a 

 physico-chemical explanation. Considering the youth of experimental 

 biology we have a right to hope that what has been accomplished 

 in this problem will occur in rapid succession in those problems 

 \vhich today appear as riddles." 



What has in reality been solved in connection with these 

 problems? It has been demonstrated, (1) that certain eggs will 

 develop without sperm, some under normal conditions, others when 

 subjected to certain chemical or physical changes in the environ- 

 ment, (2) that the development will not begin in the absence of 

 oxygen, (3) that after development begins the elimination of carbon 

 dioxid increases, (4) that unfertilized or inactive eggs live longer 

 in the absence of oxygen than in its presence, (5) that transmission 

 of hereditary characters including sex is associated with the chromo- 



38* 



