Protozoa from Fishes. 383 



ILemosporidta. 

 Parasites o/Cottus scorpius (the Father Lasher). 



Six members of the above species were examined for blood- 

 parasites, and of these three contained Hazmogregarina cotti, 

 Brumpt et Lebailly, in small numbers. The parasites 

 exhibited the usual Hsemogregarine characters, were large, 

 and in nearly all cases curled round upon themselves (see 

 PI. XVI. fig. 1, ■/). They were nearly always present in the 

 erythrocytes, but in one case a parasite was found in an 

 erythroblast. A large number of the organisms were found 

 to be free in the plasma, but this was, no doubt, due to an 

 artifact when the smears were made. 



In size the parasite measured about 12 jjl by 4 fx, although 

 smaller forms were observed. No cases of double infection 

 were ever observed, and in this the Hamiogregarine differs 

 from that found in the blood of blennies and skates. Meta- 

 chromatinic grains were commonly present, and there was 

 always a distinct capsule in the blood-corpuscle surrounding 

 the parasite. The edge of this capsule can be readily seen 

 in the figure. 



Examination of spleen-smears of the Cottus disclosed 

 several small Hsemogregarines of a type differing from those 

 found in the peripheral blood. These forms were of the 

 typical bean-shape, slightly bowed, and with a large diffuse 

 nucleus. They measured about 10 fi in length by 3 /a in 

 breadth at the widest part of the cell-body. These evidently 

 corresponded to the trophozoites and schizonts of other nearly 

 allied groups. In a good many cases distinct fragmentation 

 of the nucleus could be made out, and parasites of the rosette 

 type were to be found. The picture presented was very 

 much like that of the schizogony of Coccidium — o£ course, on 

 a smaller scale. 



With a view to finding out whether Calliobdella punctata, 

 the Cottus-leech, was the invertebrate host of Ilcemogregarina 

 cotti, some smears of the gut and sections of the body of the 

 leech were made. The results were, on the whole, satis- 

 factory. Gut-smears were found to contain the Hsemo- 

 gregarines in fair numbers. These organisms were all found 

 in a free state, the hemolysin in the gut of leech being 

 evidently a powerful one — at any rate, towards the erythro- 

 cytes of the fish. In all the smears prepared, perhaps only 

 three or four intact red-cells were found, the others having 

 been hsemolysed. The parasites, however, are seemingly 



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