THE LIVING SUBSTANCE. 43 



stance about the eggs as they leave the body.^ There are cases 

 in which the two sorts of structure are combined. In these 

 the substance, both as such and as area or organ, functions for 

 "secretion." 



In areas having marked glandular function for the organism, 

 the inclusions corresponding to Biitschli's structure are apt to 

 be much enlarged. It is noteworthy that certain brain and 

 ganglionic areas of some rotifers showed such a state of things. 



Areas whose function is not for displacement but in gross 

 chiefly of a chemical nature, are thus of the vegetative class. 

 Hence all areas where the substance as such occupies itself 

 chiefly in digestion or assimilation processes join this tentative 

 group. 



[41] Wherever areal function is markedly irritable or con- 

 tractile, the inclusions of the organized substance are uniformly 

 fluid, and the discontinuous element is evenly distributed with 

 respect to the course of organized action of the continuous 

 element.^ It is evident that the elastic, contractile, continuous 

 substance has freest pJiysical opportunity when its inclusions are 

 fluid and uniform in size. 



(a) Further, whenever in areas characterized by heterogeneity 

 of inclusions there arise organized activities of this sort, how- 

 ever fleeting, a precisely similar state of things is associated 

 with them. In development of many eggs the direct action of 

 the substance with respect to its different inclusions is striking. 

 Solid substances, such as yolk or pigment, are segregated or 

 deported temporarily from areas in which activities of the sort 

 under discussion are to appear. Sometimes these areas are in 

 relation to individual cells, sometimes in relation to the whole 

 coming organism as a substance mass. 



[42] Wherever, in short, the substance is preparing itself for 

 organized contractility or irritability (if, indeed, we may so far 

 separate the two), it provides for itself just those physical con- 

 ditions which offer greatest vantage.^ 



1 In this form I find there is a special opening for the egg to pass through, 

 quite distinct from the cloacal opening, and situated just above it. 



* See Striation ; also below, nervous areas. 



^ Obviously this might be conversely stated, yet, it seems to me, vnth less 

 justification as yet. 



