46 ACTINOPHRYS. 



mere mucous tissue. In the latter case we see the lowest 

 possible grade of organic tissue, whilst in the former it is spe- 

 cialized so as to present two distinct forms, namely, the mucous 

 form, (cytoblastema,) and the cells which have been generated 

 in it. 



At once, then, you will see that the organic functions are dis- 

 tributed not only in different regions of the body, as we have 

 already observed among the successively rising members of the 

 Rhizopod group, but among two distinct sets of tissues. In 

 the former groups everything is performed by a body that is all 

 cytoblastema, but in this group the cytoblastema has generated 

 cells which assist in performing the functions of the organiza- 

 tion. Moreover the cells are differentiated so as to present two 

 distinct features among themselves ; thus we have an outer 

 layer of cells (cv, r 1 ), which are much larger than those within, 

 and they are disposed quite methodically in a single layer all 

 over the body ; and within, the smaller cells are united, without 

 apparent regularity, so as to form a sort of core. In the inter- 

 stices of both kinds of cells there is a universally pervading 

 cytoblastema, which also at certain points has a specialization 

 of its own substance. I refer to its prolongation, from between 

 the cells of the outer layer, into those attenuated, bristling bodies 

 which I have spoken of as pseudopodia (ps). 



It is a notable fact that although the cvtoblastematous sub- 



V 



stance overlies the whole body, exterior to the larger cells, yet it 

 never projects, in the form of pseudopodia, as if in prolongation 

 of the cells, but invariably alternately with them. 



Notwithstanding the simple structure, or rather structureless 

 character, of the pseudopodia, they at times exhibit a rapidity of 

 motion equal to that of the most highly organized muscle. This 

 is most frequently seen in connection with the seizure of living 

 animals for food. Minute creatures of almost every kind are a 

 prey to this far-reaching Briareus. The moment that any mov- 

 ing body comes in contact with one of the pseudopodia, as 

 for instance the little Rotifer, a shrimp-like animal, which I have 

 represented here (r), it becomes as it were glued to it, and 



