OF CILIATED INFUSOEIA 269 



specimen shown in Fig. 69, A (x 250), in which the large elongated 

 ovoid nucleus is partly revealed. In C (x 250) another specimen 

 is shown, in which segmentation into four has taken place, one of 

 the segments being at a deeper level, and therefore hidden. This 

 specimen has been forced out from its egg-case by the pressure of 

 the cover-glass, though the segments were still contained, and 

 were revolving, within the invisible hyaline envelope. One of the 

 segments into four of another organism, from a pot which was first 

 opened on the seventh day, is shown in B, in its free swimming 

 state. It is rather more elongated than usual and its body con- 

 tained blackish granules, rather than the brownish globules more 

 commonly to be seen. In D a free undivided specimen is shown 

 which had probably been long revolving within its egg-case, from 

 which it had, however, only recently escaped. It is altogether 

 unusually free both from globules and from granules, and therefore 

 serves well to show the fine longitudinal striations of the body 

 along which the rows of cilia are found ; and also the small 

 characteristic ear-like mouth, the existence of which caused H. J. 

 Carter, who first discovered the type of this genus in India, to give 

 to the genus the name Otostoma. His type specimen was found 

 within the decaying filaments of a species of Nitella. The speci- 

 mens derived from the transformation of the eggs of Hydatinje 

 evidently belong to the same genus, as may be seen from its 

 description, together with that of the species discovered by Carter, 

 as given in Saville Kent's " Manual of the Infusoria " (vol. ii., 

 p. 500, PI. XXII.). In the specimens as they come from the Hyda- 

 tina egg-case no contractile vesicle is usually to be seen, though a 

 single complicated vesicle develops later ; but in regard to the 

 approximate size and shape of the organism, its longitudinal stria- 

 tions, the character of the nucleus, together with the situation and 

 shape of the ear-like mouth, there is the closest accord between it 

 and the form to be found at times within decaying Nitella cells. 



That similar transformations to those described above occur 

 within the small male eggs may be seen by the photographs com- 

 posing Fig. 67, all of which have been taken at a magnification of 

 250 diameters. I only show a few of the stages, omitting other 

 intermediate states of which I have representations, as the changes 

 are so obviously similar to those occurring in the larger eggs. A 

 shows a newly-laid specimen of one of these small eggs. B shows 

 one of the early stages of the transformation in which characteristic 



