1 88 BIOLOGICAL LECTURES. 



aggregate exerts over its parts a force," etc., Spencer follows 

 this up with the non sequitur, " we seem obliged, in the case of 

 the organism, to assume an analogous force." 



After showing that this property, i.e., " this tendency to 

 aggregate into specific forms," cannot reside in the chemical 

 compounds, because, if it resided in "the molecules of albumen 

 or fibrin or gelatine or other proteid," there would be noth- 

 ing to account for the unlikeness of different organisms ; and 

 after showing further that it cannot reside in the morpho- 

 logical units or cells, because the same power is shown by uni- 

 cellular organism, Spencer concludes that this proclivity is 

 " possessed by certain intermediate units which we may call 

 physiological," etc. 



Striking as is the comparison between the growth of a broken 

 crystal and the regeneration of an injured animal or plant, the 

 emptiness and superficiality of the comparison are at once appar- 

 ent on closer examination. The looseness of Spencer's argu- 

 ment is equally evident, and his rejection of the idea that the 

 chemical substances composing protoplasm cannot account for 

 the facts leaves him only his imaginary physiological units to 

 bring about the results. The latter, after all, could only be 

 formed by combinations of the chemical substances, and if so, 

 why introduce into the argument unknown "units " having the 

 property of bringing about regeneration ? To my mind nothing 

 could confuse the whole subject more surely than reasoning 

 and arguments like those advocated by Spencer. 



The recent work of Rauber on the " regeneration " of crys- 

 tals gives us now a basis of fact on which to rest any com- 

 parison we may make. Rauber's results show that during the 

 growth of a broken crystal the typical form may be assumed 

 and the broken surfaces obliterated. In some cases the growth 

 may be more rapid over the broken surface, since this rougher 

 surface presents a greater area for the deposition of new mole- 

 cules. When a piece is broken off, the closing in of the 

 exposed part presents no phenomena that are in any way 

 different from the growth of the crystal everywhere else. The 

 position of the new molecules that are added is determined by 

 the condition at the points to which they are applied. It is 



