AXIAL GRADIENT IX CILIATE INFUSORIA. 



39 



peristomal cilia cease their movement the body ceases to 

 revolve in the water, but the smaller cilia covering the body con- 

 tinue to beat until the disintegration wave reaches them. From 

 the peristome region the process of disintegration spreads down- 

 ward over the body as indicated in Figs. 2-5, the aboral end 



being the last region to lose its structure. The disintegration 

 of the aboral half is in practically all cases much more rapid 

 than that of the oral half; very commonly the disintegration of 

 the oral half requires two to four minutes, that of the aboral half 

 one to tw r o minutes, i. e., the differences in susceptibility beween 

 different levels are much greater in the anterior than in the 

 posterior half. Moreover, the anterior half and particularly 

 the peristome region lose their pigment more completely and 

 swell and spread out to a greater extent in disintegration than 

 the posterior half. Finally the animal is represented by a shape- 

 less mass of protoplasm in which the meganucleus remains 

 intact for a long time and about which a halo of blue pigment 

 appears. With the concentration and temperature above men- 

 tioned the whole process of death and disintegration requires 

 from two to six minutes, the rate of advance of the disintegration 

 varying in different individuals and in some cases in different 

 regions of the body. 



The striking features of the change are its very definite course, 



