44 ANDREWS. 



[43] The most readily noted feature of such organization is 

 uniformity in kind, size, and arrangement of inclusions. But 

 this is in most cases secondary in importance to differences 

 in quality, structure, and position of the continuous substance. 

 These things are as true of contractile and transmissive areas 

 in the Metazoa as in the Protozoa ; and portions of one or 

 many "cells," may be involved in these modifications. 



(a) In areas formed for interaction with environment, whether 

 limited to pellicles or involving an underlying alveolation, fluid 

 inclusions are gathered together, arranged with great uniformity, 

 and often subdivided to a point of great minuteness, which 

 latter change involves, of course, a physical extension of the 

 lamellar substance. (For the full significance of these things 

 the reader must see the later sections.) 



(b) Such are ectosarcal formations, and such the arrangement 

 of the elements wherever the substance meets internal contacts 

 with organized reactions characteristic of ectosarc. 



(c) All areas to be grouped with ectosarc, that is, all areas 

 which are formed of interalveolar material, with or without 

 fluid inclusions of the structure of Biitschli, have the same 

 character. 



[44] There is a marked habit of the substance to meet all 

 contacts involving a number of the alveoli of a given structure, 

 with organization of its elements in such a way as to produce 

 an ectosarc-like formation. This may be formed of inter- 

 alveolar material alone as a pellicular modifier, or may involve 

 more or less of the structure of Biitschli. 



(a) In the formation of ectosarc there is a tendency to reduce 

 the structure by subdividing the alveolar inclusions. 



(b) There is a tendency, too, in such areas, whether so sub- 

 divided structurally or not, to increase of viscosity. 



[45] I find that true optical homogeneousness, or structure- 

 lessness of protoplasm, is most often produced by minuteness of 

 structure, rather than by mere stretching of alveolar lamellae. 

 The latter state produces, of course, a less dense and refrac- 

 tive substance, while the former produces a more dense and 

 refractive substance. So-called, as well as veritable, optically 

 structureless protoplasm is commonly denser, more viscous, and 



