276 LILLIE. [Vol. XVII. 



mass of undifferentiated cells, such as the chick blastoderm in 

 an early stage, or in a mass of material composed of specific 

 tissues, as in a portion of a planarian, it appears to me that 

 they are in principle everywhere the same ; I would say that 

 the same cytoplasmic organization is concerned alike in the 

 development of the planarian from the &gg and from the frag- 

 ment of a mature individual. Where are we to place it except 

 in those protoplasmic elements of whose nature we are so 

 ignorant .'' 



" If the formative processes cannot be referred to cell divi- 

 sion, to what can they be referred .-' To cellular interaction ? 

 That would only be offering a misleading name for what we 

 cannot explain ; and such an answer is not simply worthless, 

 but positively mischievous, if it puts us on the wrong track. 

 Loeb's experiments on heterogenesis furnish a refutation of 

 the interaction theory. The answer to our question may be 

 difficult to find, but we may be quite certain that when found 

 it will recognize the regenerative and formative power as one 

 and the same thing throughout the organic world. It will 

 find, as Wiesner has so well insisted, a common basis for every 

 grade of organization, and it will abolish those fictitious dis- 

 tinctions we are accustomed to make between the formative 

 processes of the unicellular and multicellular organisms. It 

 will find the secret of organization, growth, development, not 

 in cell formation, but in those ultimate elements of living mat- 

 ter, for which idiosonies seems to me an appropriate name." 

 (Whitman, "The Inadequacy of the Cell Theory of Develop- 

 ment.") 



I think that we need not ascribe to the egg a more complex 

 organization than it may be ultimately possible to discover in 

 it by observation and experiment, and should attempt to explain 

 the subsequent development, phenomenally at least, in a purely 

 epigenetic manner. I am very far from asserting that in the 

 case of the o.^^ of Unio we have fully described the organiza- 

 tion in the cytoplasm, to say nothing of the nuclear material. 

 But what I do mean to assert is that we should rid ourselves of 

 all mysticism in dealing in a purely scientific manner with the 

 problem of the organization of the ^gg, or the nature of the 



