ZOOLOaY AND BOTANT^ MICKOSCOPYj ETC. 755 



witli reproductive properties on the other. We know, in fact, that 

 the non-cellular elements are produced by those which are cellular, 

 and that their generation and reproduction are subordinated to those 

 of the latter ; they nourish themselves and develope, but always 

 remain devoid both of contractility and nervous power ; they may 

 undergo regeneration, but do not reproduce directly. 



Of course that which is called a physiological unit is confused, as 

 we have seen in the case of the Protozoans, with that description of 

 the organization of the cell which describes it as an anatomical unit, 

 and the expression is only true when used in a general or abstract 

 sense. However, Podophrya Lynghyei (e. g.) in the larval stage, is a 

 good example of both an anatomical and physiological unit. But it is 

 certain that by virtue of their peduncle, of their theca which is 

 separable from it, and of the body which is separable from the theca, 

 the adults of Podophrya and the Acinette are Protozoa in which are 

 found at least two kinds of anatomical and physiological units : the 

 one of these, namely, the non-contractile theca and its peduncle, is 

 subordinate to the other, the sarcode body, and it remains essentially 

 different from it in anatomical and physiological characters. 



With regard to the study of the unicellular animals, it is evident 

 how wide of the truth those are who consider everything in 

 anatomy to consist in the study of the form and morphological 

 arrangements of these beings at whatever stage they are examined ; for 

 though they adopt these primary and necessary ideas, they omit that 

 which, by explaining the nature of the factors which go to make up 

 the forms of organized bodies, furnishes a biological analysis which is 

 in accordance with theoretical and scientific principles and determines 

 the essential characters of those bodies. Now, it is this power, 

 which is the real basis of general anatomy, which constitutes it a 

 science capable of ranking with the other branches of anatomy, which 

 forms it into a compact whole, and enables it to explain the origin 

 of the parts which possess volume, colour, consistence, and shape of 

 various kinds. 



It becomes still more seriously manifest how much is still left to 

 be done or to be done over again when we turn to the more important 

 study of embryogeny, and point out only those forms and analogies 

 which are expressed by the terms morula, gastrula, &c., and secondly 

 the forms assumed by the layers of the blastoderm, without going into 

 the precise meaning of the different kinds of cells which constitute 

 these forms, or of those cells which become the exact point from 

 which this or that transitory or permanent organ takes its origin. 

 All this series of forms is in reality only the result of groupings of 

 cells which are stages between each form of organ and its successor, 

 the result as much of the life of nutrition, which resides in the 

 animal, as of that of reproduction, locomotion, and innervation. The 

 only result attained by those who would regard biology as independent 

 of chemistry — which discovers the intimate character of bodies — and 

 anatomy as limited to morphology and not needing the ideas 

 furnished by elementology, will be the knowledge of the surface of 

 the matter, without arriving at those conclusions which supply 



