232 BIOLOGICAL LECTURES. 



economy nor social instinct that binds the two halves of an 

 egg together, but the constitutional bond of individual organ- 

 ization. It is not simple adhesion of independent cells, but 

 integral structural cohesion. 



" That organization precedes cell formation and regulates it, 

 rather than the reverse, is a conclusion that forces itself upon 

 us from many sides. In the Infusoria we see most complex 

 organizations worked out within the limits of a single cell. 

 We often see the formative forces at work, and structural fea- 

 tures established before fission is accomplished. Cell division 

 is here plainly the result, not the cause, of structural dupli- 

 cation. The multicellular Microstoma behaves essentially in 

 the same way as the unicellular Stentor or the multinucleate 

 Opalinopsis of Sepia. The Microstoma organization duplicates 

 itself and fission follows. The chain of buds thus formed bears 

 a most striking resemblance to that of Opalinopsis, and the 

 resemblance must lie deeper in the organization than cell 

 boundaries. 



" We must look entirely behind the cellular structure for 

 the basis of organization." 



It is the continuity of organization, whether the organism 

 be composed of one cell or many, which is insisted upon 

 throughout this paper, and in agreement with Sachs ('82), cell 

 formation is regarded as of only " secondary significance." 



Wilson ('93, p. 595) stated in regard to Amphioxus that 

 " the unity of the normal embryo is not caused by mere juxtaposi- 

 tion of the cells. They (the facts) indicate that this unity is not 

 mechanical bnt physiological, and point toward the conclusion 

 that there must be a strncttiral continuity from cell to cell that is 

 the medium of coordinatioji and that is broken by mechanical dis- 

 placements of tJie blastomeres." ^ 



McMurrich ('95), in a lecture of this series delivered in 1894, 

 after a discussion of the early development of centrolecithal 

 ova, concludes " that in embryological development the differ- 

 entiation which occurs is a differentiation of the entire organ- 

 ism and not of the constituent parts of which it is composed ; 

 physiologically, if not morphologically, every organism is a 



1 Italics in this and in all succeeding quotations are as in the original. 



