126 E. A. MINGHIN AND H. M. WOODCOCK. 



stao-e of the infection, unci may be rej^arded as derived from 

 sporozoites wliich have penetrated the blood-corpuscle. They 

 are for the most part very uniform in size and appearance 

 and probably destined to become sciiizonts. 



The large forms are, we consider, of two distinct types, and 

 not directly connected with one another — that is to say, an 

 individual of one kind, e.g. a broad foi-m of parasite, does 

 not pass into one of the other kind, the slender type, by a 

 process of elongation and simultaneous bending-up, such as 

 is described by Borner (4) in H. stepanowi; nor, on the 

 other hand, is the broad form to be derived from the slender 

 type by a pi'ocess of change comparable to that frequently 

 described among Reptilian ha^mogregarines, where a U-shaped 

 form gives rise, by the fusion of its two arms, to an oval or 

 bean-shaped form (cf., for example, H. tunisensis of Bufo 

 mauritanicus. Billet [2], H. bagensis of Emys leprosa, 

 Billet [3], etc.). Our reasons for regarding the two large 

 forms of H. rovignensis as independent are three : In the 

 first place, we liave noticed no transitional forms indicating 

 such a connection as just mentioned ; secondly, there is 

 always a well-marked difference between the nucleus of forms 

 belonging to these two types; and lastly, young individuals 

 of each typo are clearly distinct. We suggest that these 

 large forms show sexual differentiation, the slender type with 

 the small nucleus being of male chai-acter, and the stout form 

 with the large nucleus being of female sex. 



With regard to their origin, it is very probable that they 

 have been developed from two forms of merozoites, smaller 

 and larger, for the young individuals of the slender or male 

 type in figs. 12, 13 are manifestly different from the other 

 small forms, and not likely to have arisen from them. There 

 is one point, however, in this connection which at first was 

 not at all clear. In the second gurnard examined (figs. 12- 

 14, 16-26, 44-50) the number of the young parasites found 

 belonging to the type which we regard as male is very small 

 indeed as compared with the number of the ordinary small 

 forms present, whereas about equal numbers of the full-grown 



