Organisms Consisting of One Cell 



plex of similarly differentiated cclU." !l Tin's definition of 

 tissues, occurring in one of tin- mo-t generally used text- 

 book- of miscroacopical anatomy, turns up in Mihstance 

 again and again in the common instructional writings of the 

 dav. ''The foundation-stone of the tissue is the cell." 10 

 According to thi> doctrine the- cell is the building-stone of 

 tin- ti->ue. >o no matter what may be found within the cell, 

 it cannot be a ti>-ue. I "ndouhtedly this way of treating the 

 term ti.vsiK has been useful, es]>ecially didactically, and 

 undoubtedly too it is on the whole justified so far as multi- 

 cellular organisms are concerned, though even here 'the 

 scientifically scrupulous teacher finds himself under the 

 necessity of doing much uncomfortable w r riggling to make 

 many of the connective tiues fit into it. But when the view 

 is extended to the whole animal kingdom, to the protozoa 

 as well as to the meta/oa, one sees how inadequate and 

 cramping such a conception of tissue is. 



Tin- fact is. when we con-ider the real meaning of the 

 word tissut'. and -till further, when we consider what the 

 anatomical parts are to which the early anatomists thought 

 the term could be appropriately applied, we see that with 

 the possible exception of some of the connective tissues 

 of the higher animals, we can hardlv point to a more typical 

 tissue than that of the network of strands into which the 

 peripheral -arcode of many of the Rhi/opods forms itself, 

 or than the ext ra-capsular "plasm" of a Radiolarian like 



'halafticotta. I mention this gums especially because a spe- 

 of it which has. been well figured and described by Haec- 



1, is frequently used in text-books as a type of the group. 

 "meshes constituting the sarcodictyum" the "alveoli 

 of the calymma" and the pseudopodia arising in the deep 

 zone, or sarcomatrix and "forming a network through the 

 othr capsiilar part-," are the terms in which the "plasm" 

 of these animals is described. And notice how contrary to 

 good biological usage it is to employ an anatomical nomen- 



