116 E. A. MlNCiflX AND IJ. M. WOODCOCK. 



in the general circulation, and these belong to two distinct 

 types. Most unfortunately, as it has turned out, no smears 

 from the organs were made in the case of this fish. 



Considering first the relation of the parasites to their host- 

 cells, we find that nearly always a single individual is present 

 in a blood-corpuscle. Instances of a double infection occur, 

 but they are very rare ; we have only noticed two. In these 

 cases two small forms lie side by side in onehalf of the corpuscle, 

 the nucleus being displaced to the opposite end (fig. 27). 

 The only effect which tlie parasites appear to have on the 

 corpuscles is a mechanical one. In no case does the haemo- 

 gregarine attack the nucleus or cause its hypei'trophy or other 

 degenerative effect.' In corpuscles infected with the small 

 forms the nucleus is generally displaced to one side (cf. figs. 

 1, 2, 16, 17). In the case of the large forms, the nucleus of 

 the host-cell is often displaced quite to one side, lying at the 

 periphery of the corpuscle (figs. 18-26). It may be slightly 

 flattened or compi-essed (figs. 18-20), but shows no other sign 

 of alteration. 



In a few cases indications of the presence of a delicate 

 membrane or envelope around the iutra-cellular parasite 

 appear to be furnished by the stained prepai-ations in a rather 

 interesting manner. Usually no signs of such a structure 

 can be detected; even where, as occasionally happens, the 

 parasite has shrunk slightly from the enclosing corpuscle, 

 leaving a clear space around itself, it cannot be said, as a 

 rule, that a definite sheath is apparent. But now and again 

 the stain is deposited in a marked manner in the protoplasm 

 of the corpuscle immediately around the parasite, which 

 points to the existence of a layer of somewhat altered 

 character, acting as a hindrance to the further penetration of 

 the stain. This is especially well seen in those cases where 

 the cytoplasm of the pai-asite happens to have partly or 

 entirely shrunk (as in figs. 6, 39), leaving a deeply stained 

 line bordering the outer edge of the clear space. We have 

 noticed this appearance occasionally around both the small 

 ' Hence this parasite does not belong to the genus Karyolysns. 



