A NEW MELANIN-PRODUCING HAEMATOZOON. 99 



moeba metchnikovi belongs to our genus Haemocystidium, 

 and it should henceforth be styled Haemocystidium metch- 

 nikovi, Simond." 



As our species seems to agree generically with Simond's 

 one, and is likewise from a tortoise, it follows that it 

 should also be grouped under the genus Haemocystidium. 

 But in the above somewhat vague definition of the genus, 

 displacement of the nucleus assumes an important position, 

 though in spite of the absence of this characteristic in 

 Simond's parasite, this latter is included by Oastellani and 

 Willey in their genus. It must therefore follow that, if the 

 genus is to hold good, displacement of the nucleus is not a 

 necessary character. We accordingly suggest that the 

 genus be amended as follows: — In early stages, the parasite 

 is irregular or slightly amoeboid ; in later stages, oval 

 (? schizonts) or rounded, turgid, more or less bladder-like 

 (? gametocytes) : it produces melanin granules, vacuoles 

 are frequently present, and there may or may not be dis- 

 placement of the nucleus of the red cell ; and the host is 

 reptilian. 



Little, therefore, remains to distinguish this genus 

 from Plasmodium, though it can be at once distinguished 

 from Halteridiam by the absence or at least great rarity of 

 halter-like forms and by displacing the nucleus in one species 

 at least. As, however, it is probable that later researches 

 into the complete life-history of these parasites will discover 

 other and more marked differences between the forms 

 included under Haemocystidium, all obtained from reptiles, 

 and the genus Plasmodium as found in warm blooded animals 

 (mammals and birds), we have considered it better to place 

 our species under Haemocystidium, as thereby are kept 

 together a small group of melanin producing haematozoa 

 of reptiles which are doubtless species more closely inter- 

 related between themselves than to somewhat similar 



