310 Transactions of the Society. 



they were atrophied, but such is not the case, as they prove distinct 

 and active enough as soon as need be. 



So far we have considered Folliculina in its expanded condition ; 

 but more often the animalcule is found retracted in its shell 

 (fig. 8). When the lobes contract, they fold and become hardly 

 recognizable, so that one cannot wonder at Folliculina having been 

 taken by Henneguy for a special genus and by Zacharias for a 

 Stentor in its cyst, or by others as something quite different from 

 what it is in reality. 



Like the marine Folliculina elegans, our fresh-water species is 

 coloured a pale blue, or rather we might say a bluish-green or a 

 greenish-blue, and the colour is due to very small grains or concre- 

 tions. According to my observations, the origin of these grains 

 would be as follows : Vacuoles are first formed whose content is a 

 clear blue fluid, and by-and-by small darker granulations appear 

 in the liquid itself, true concretions in fact, which are deposited in 

 greater and greater numbers, and at last fill up the entire vacuole. 

 This latter then loses its wall, and the grains disseminate in the 

 adjoining plasma. From time to time one of these large vacuoles 

 with its dark concretions is seen to move slowly towards the 

 anterior part of the body, and after several hours its contents are 

 suddenly expelled by the anal pore, which is situated near the base 

 of one of the lobes, and opens, not inside the vestibulum, but out- 

 side into the water. 



The coloured matter when in great abundance can also very 

 likely be expelled by a simple opening in the posterior extremity 

 of the body ; lumps of green matter are very often seen lying in the 

 space between the shell and the body, and when the animalcule 

 leaves its envelope to build another somewhere else, it always 

 leaves behind in the old case a large quantity of green refuse. 



These granulations must be considered as a product of excretion, 

 useless and perhaps noxious in themselves, though at the same 

 time they are an indication of the state of health of the animal, for 

 the more it is coloured the more healthy it is ; in fact, to be in a 

 perfect state, the animalcule must be able to produce an abundant 

 quantity of secretional matter. When very weak, or in a state of 

 illness, the body gets pale and hardly furnishes any appreciable 

 quantity of green substance. Absolute alcohol discolours these 

 grains, but apparently without dissolving them. 



The envelope or shell is quite colourless when recently formed, 

 but acquires later the bluish hue which is characteristic of the 

 animal ; but I cannot agree with Sahrlage, who attributes the 

 coloration in this case to small grains. It is quite true that the 

 shell is always more or less covered with particles of various kinds ; 

 but the coloration of these, as well as of the shell itself, is in my 

 opinion rather due to a diffusion of colour from the animal acting 

 like a "mordant " on such objects in the vicinity which are apt to 



