PRECIPITATION STRUCTURES SIMULATING ORGANIC GROWTH. 233 



which will also be constant, i. e., definite or predetermined. 

 The whole developmental sequence may then be said to have 

 been determined by the original constitution of the system; that 

 is to say, two or more such similar systems, placed under the 

 same external conditions, will develop in the same way and will 

 reach similar final stages at the same time. Conversely, two 

 systems differing in initial constitution, placed under similar 

 external conditions, will be transformed in different manners 

 and at different rates and will form different final products. 

 The case of two eggs of the same species developing side by side 

 in sea-water illustrates the first case ; that of two eggs of different 

 species the second. The corollary follows, that any attempt to 

 account causally for the special structure or activities of an 

 organism at any stage, adult or embryonic, must always involve 

 a regressus to the original conditions with which development 

 starts. One is thus inevitably brought back to the organization 

 of the germ as a starting point. 1 



The general conclusion follows: any germ with a definite or 

 fixed physico-chemical organization, implying constancy in the 

 composition, distribution, and physical state of its structural 

 and other chemical components, which is in process of incor- 

 porating materials from the surroundings (or its own yolk re- 

 serves) and transforming these materials so as to form further 

 structure, will necessarily follow a constant course of transfor- 

 mation if the external conditions are also constant; this will 

 apply both to the type of structure making its appearance at 

 any stage, and to the physiological processes and other activities 

 whose nature depends on that structure. Apparently we have 

 here the general type of situation presented by the developing 

 germ or other living system in process of growth. Given a 

 specific organization at the outset, together with constancy of 

 conditions, external and internal, under which the incorporated 



1 The origin of this organization is of course similarly to be referred to preexisting 

 conditions, and strictly speaking any such regressus is ad infinitum. In any 

 sequence of physical processes each stage is at once conditioned by the preceding 

 and the condition of succeeding stages i. e., is both determined and determinant. 

 For an admirable discussion of the relation of this feature of reality to develop- 

 mental processes in general,*;/. Hobhouse's "Development and Purpose," Part 

 2, especially chapters 4 and 5. 



