128 E. A. MINCHIN AM> II. M. WOOUOOGK. 



pronounce definitely between these two views. When, how- 

 ever, vve compare tlie facts which we have learnt concerning 

 H. ro vignensis with what is known in the case of other 

 piscine haemogregarines, we are strongly inclined to consider 

 the latter view the correct one, and that the two distinct 

 types of form are micro- and macro-gametocytes. Fission or 

 schizogony is now known to occur in many piscine haemogre- 

 garines, and in most oF the instances described it appears to 

 be of one kind, no indications of sexual dimorphism being 

 mentioned (cf. H. bigemina, Laveran & Mesnil [6], H. 

 quadrigemina, Brumpt tt Leb. [9, tig. 8, p. 382], H. 

 simondi, Lav. & Mesn. [6], etc.). Neumann, in his account 

 of piscine hoemogregarines (15), regards the schizogony in 

 these instances as resulting in the formation of " gametes," 

 but does not attempt to explain why only one kind is described 

 and figured. Further, in his account of H. poly par tit a 

 from Gobi us pagenellus, he regards similar crescentic 

 forms, four of which are developed in a blood-corpuscle, 

 also as ''gametes." He endeavours to show that these forms 

 exhibit sexual differentiation, but such distinctions as are 

 apparent in his figures seem to us to be due merely to slight 

 differences in size (or age) and in tint of colour (otherwise 

 degree of staining). We do not find anything approaching 

 the pronounced and constant differences, both in form and 

 in the size of the nucleus, which are shown by the large 

 types of H. rovignensis. We certainly consider the curved 

 forms of H. poly partita — equally with those of Neumann's 

 other new species, H. clavata — as " merozoites," probably 

 really '"indifferent" in character,^ and quite comparable with 

 those described in the above-mentioned parasites. 



^ It is quite possible, of course, that in some liEemogi-egarines the 

 schizogonic forms exhibit sexual difPerentiation. Up to the present, 

 however, we do not consider this has been shown to be the case. 

 Wenyon (22) has figured " barillets " both of micro- and mega-mero- 

 zoites in connection with H. gracilis from the liver of Mabuia. 

 Certain of "Wenyon's figures suggest strongly the schizogony of a 

 Coccidian, and we think this explanation is not at all unlikely, both in 



