l82 C. M. CHILD. 



in a particular protoplasm. Granting their existence and the 

 significance which I have assigned to them they represent merely 

 certain physiological conditions, under which the hereditary 

 mechanism of a protoplasm gives rise to the order or pattern 

 which we call axiate or axiate-symmetrical. 



The egg in most cases requires fertilization or the action of 

 some other factor external to it to initiate development, but the 

 specific hereditary constitution of the egg protoplasm with its 

 potentialities of development is present, whether fertilization or 

 initiation of development by other means occurs or not. Physio- 

 logically speaking the spermatozoon or some other factor ex- 

 ternal to the egg merely sets the mechanism in motion or gives it 

 the necessary speed and development proceeds. Similarly the 

 gradient in the egg, whether it persists from earlier cell genera- 

 tions or arises anew in the egg through differential exposure, is 

 merely a physiological condition which determines that the hered- 

 itary mechanism shall give rise to a particular order or pattern. 

 Alteration of the gradient relations alters the pattern though the 

 hereditary mechanism remains the same. The gradient is then 

 nothing more than one of the physiological conditions under 

 which the development of axiate organisms occurs, and the sur- 

 face-interior relation, whether a gradient or not, is merely an- 

 other even more general physiological condition of organismic 

 development. 



The idea of a quantitative gradient in physiological condition 

 as the condition initiating axiate development and of its origin 

 in the final analaysis through the action of an external factor 

 does not require or depend upon any. particular assumptions or 

 theories concerning inheritance or evolution. Some of the critics 

 of the conception have regarded it as Lamarckian, but it is not, 

 though of course it might be used if desired in a Lamarckian 

 way. Strictly speaking, it has nothing directly to do with either 

 inheritance or evolution, except in so far as it maintains that 

 axiation or polarity and symmetry are not inherent properties or 

 characteristics of protoplasm. It is fundamentally a physio- 

 logical conception formulated on the basis of many different 

 lines of observational and experimental evidence, and while its 

 formulation in the present state of our knowledge is necessarily 



