﻿Notes upon a Hcuplosporidicm. 



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In the most conspicuous and obvious stage the animal 

 is spherical, with a very well marked outer membrane or 

 envelope. This envelope varies in thickness, and appears 

 to me to be secreted by the parasite. It is smooth, and 

 apparently almost structureless, occasional slight circum- 

 ferential striations indicating that it may very possibly 

 develop in concentric rings. The envelope or cyst-wall 

 appears to be of rather a stiff gelatinous consistency, and 

 stains faintly with Ehrlich's hsematoxylin, also with eosine, 

 but remains, as a rule, quite unstained by Heidenhain's 

 iron hsematoxylin method. The outermost limit of the 

 envelope is occasionally somewhat crinkled. 



The word cyst, as used in Protozoan literature, has such 

 a wide and indefinite connotation that I think it is expedient 

 to define exactly the sense in which it is used here. The 

 cyst- wall is, in the present case, a gelatinous envelope 

 secreted by the parasite w^hile in the trophic state ; growth 

 may take place, and all the ordinary metabolic processes 

 appear to go on without interruption. The parasite leaves 

 the cyst in the trophic condition, and may apparently again 

 secrete a similar envelope. The breaking up into repro- 

 ductive bodies occurs, as will be seen later, after the animal 

 leaves the cyst. In the protozoon under discussion the 

 cyst- wall is simply the envelope of the trophozoite, and is 

 in a sense comparable to the shell secreted by, for instance, 

 an Arcella. The parasite is immobile while in the cyst, but 

 seems capable of a certain amount of movement upon leaving 

 it. Surrounding the cyst is a nodule or capsule of connective 

 tissue. The presence of the parasite causes a proliferation 

 of the connective tissue of the host, which forms a usually^ 

 circular nodule, sometimes of very considerable size. In 

 this paper the term nodule applies to the connective tissue 

 masses, and the word cyst to the envelope of the circular 

 parasite. 



The thickness of the cyst-wall bears no very constant 

 relation to the size of the Idliyosporidium, but may, as 

 will be seen later on, have a relation to the length of time 

 spent by the parasite in the one position. As regards size, 

 the creature varies between very wide limits ; one of the 



