MICROSCOPIC ORGANISMS IN INTESTINAL CANAL. 253 
tainly in some cases, retains a certain degree of contractility 
and capacity of altering its form for some time after the forma 
tion of the reproductive cells has begun, | am inclined to regard 
the latter explanation of the phenomena in these exceptional 
cases as the true one. 
The process of spore formation is not preceded by any true 
encystment ; the parent body merely loses its active progressive 
movements and form-changes, and a very delicate surface layer 
becomes, in some degree, differentiated upon it. The content- 
substance within this next begins to show a constriction, divid- 
ing it into two lobes, and a gradual extension of the process ends 
in the separation of these as independent masses (Fig. 7). The 
Fic. 7.—Formation of sporoids x 1000. 
entirety of the material of the parent does not, however, as 
before mentioned, seem to be expended thus; but a varying 
amount remains as a gelatinous intercellular matrix, which blends 
with the surface layer (Pl. XVIII, fig. 20). Under favorable 
circumstances, each of the daughter bodies originally formed, as 
described above, in its turn divides into two, and in this way 
groups of sporoids, containing large numbers of individual cells, 
may be actually observed to arise in the course of forty-eight to 
seventy-two hours (Fig. 8). Hach of the bodies thus formed by 
| 
Fic. 8.—Group of sporoids developed from an Ameeba x 1000. 
division acquires a delicate investing layer, but the process of 
