10 



THE MICROSCOPE AND ITS REVELATIONS. 



departure from the usual method. A transverse constriction divides the 

 body into two halves as shown in two individuals of colony A, each half 

 possessing its own nucleus and contractile vesicle; the posterior seg- 

 ment, which at first lies free at the bottom of the cell, then presses for- 

 wards towards its orifice, as shown at c, and finally, by amceboid move- 

 ments, escapes from it, sometimes stretching itself out like a worm (as 

 seen at D), sometimes contracting itself into a globe, and sometimes 



FIG. 284. 



Microgromiasocialis: A, colony of individuals in extended state, some of them undergoing trans- 

 verse fission; B, colony of individuals (some of them separated from the principal mass) in com 

 pact state; c, D, formation and escape of swarm-spore, seen free at E. 



spreading itself out irregularly over the pseudopodia of the colony. 

 But it finally gathers itself together and takes an oval form; and either 

 develops a pair of flagella, and forsakes the colony as a free swimming 

 Monad ( 416), or assumes the form of an Actinophrys, moving about 

 by three or four pointed pseudopodia, probably in each case coming after 

 a time to rest, excreting a shell, and laying the foundation of a new 

 colony. There is reason to think that a multiplication by longitudinal fis- 



