758 MIMMKJ. KOEKliTSON. 



site in the proboscis, nor do tlioy appear in tliis region in the 

 sections. 



V. General Remarks and Conclusions. 



When the forof'-oing account was all but complete, 1 

 received Dr. Reichenow's (12) interesting preliminary note 

 on H. stepanovi. The results I have obtained coincide in 

 all essential points with those of Reichenow, and the evidence 

 he hais obtained upon the question of conjugation is much 

 more conclusive than that brought forward by myself, as he 

 has figured the first two divisions of the zygote-nucleus. The 

 typo of conjugation is clearly the same in the two cases. The 

 only point of divergence in the two life-cycles is the schizo- 

 gony in the vertebrate host; in IT. stepanovi this takes 

 place in the bone-marrow and always occurs inside the blood- 

 corpuscle, the number of merozoites not exceeding twenty- 

 four. This difference is the main justificntion for preserving 

 the species name of H. nicorije. 



There is scarcely a single point in the development of H. 

 stepanovi as described by Siegel (13) which is in agree- 

 ment Avith the results obtained by Reichenow, or with what I 

 have myself observed in H. nicorise. I have never seen 

 the formation of the minute microgametes, nor the sporu- 

 lating stages in the blood-spaces of the leech, nor the worm- 

 like sporozoites which he describes. It would appear that 

 this worker must have been dealing with conditions differing 

 widely from those presented by the leeches I examined. 



It will be observed that the life-cycle of H. nicorise 

 differs in one or two points from that of Hepatozoon 

 perniciosum, the hpemogregarine of the rat, described very 

 completely by Miller. The most important divergence occurs 

 in connection with conjugation and the formation of sporo- 

 blasts, which in turn produce sporozoites. The sporozoites 

 never become motile in the mite, and the parasite returns to 

 the rat by way of the alimentary tract when the rat eats the 

 mite. 



