20 H. M. WOODCOCK. 



taken for one septate Gregarine, Avitli equal protomerite and 

 deutomerito, wore it not for tlio important fact of there being 

 a nucleus in each half. The two cleai-er spheres denote the 

 position of the nuclei as they showed up in life. In fig. 3 is 

 drawn a much younger stage, where the two associates, though 

 firmly attached to one another and not sepai-able by gentle 

 touching, are not yet so completely united. 



On the other hand, this precocious association or neogamy^ 

 may be still more intimate in character. In many cases, 

 especially in trophozoites which had early evaginated the 

 wall of the vessel, but also sometimes in adults still in the 

 lumen, there was no septum at all, and the two nuclei were often 

 in contact. Figs. 5 a and h show couples of this nature. In 

 the latter n is part of the second nucleus, just beginning to 

 be cut through. Here complete fusion of parasites has taken 

 place, with the result that one appears to be looking at a 

 single binuclear Gregarine. Such unions evidently occur 

 extremely early in the life-history (see below, p. 64). I may 

 here say, indeed, that I have never succeeded in finding an 

 isolated individual, either of this species or (still less) of 

 C. minchinii. I have searched hundreds of sections in 

 the endeavour, but up till now have not seen a single uni- 

 nuclear form. Fig. 30, pi. 3, shows the smallest specimen of 

 C. irregularis which I obtained, and this has a diameter 

 of barely 20 /u. Yet it has two relatively large nuclei, in 

 this case touching each other and with no sign whatever of 

 any dividing septum between. 



{h) C. minchinii. 



The extreme degree to which neogamy attains in C. irregu- 

 laris is, so far as I am aware, the only condition to be 

 observed in C. minchinii. The smallest examples of this 



> I propose to use tlie terms neogamy and neogamous in describing 

 this phenomenon, since, besides implying the early occurrence of the process, 

 Ihey also indicate its essential meaning, to which I attach great importance 

 (see below, p. 74, et seq., where this interesting question is fully discussed). 



