726 H. M. WOODCOCK. 



paratively small size of the kinetonuclear element, as well as 

 tor the fact that it is not always distinguishable as asepurate 

 organella, differentiated from the main nucleus. On the other 

 hand, such a phy logenetic connection of H a 1 1 e r i d i u m with a 

 trypanosome would also render it quite possible that, in certain 

 cases, such as the incidence of an unusual stimulus or under 

 some other special circumstances, the parasites might attempt 

 to pass into — to revert to, as it were — atrypaniform condition. 

 Thus would be explained the peculiar form of individual I 

 have above described, which appears to have developed a 

 flagellar thread. 



This view agrees in substance, it will be seen, with 

 Hartmann's ideas (5) of the Ha3mosporidia as a whole, which 

 he has united with the haemoHagellates in one group — the 

 Binucleata — the common character being the possession of a 

 binuclear condition, i. e. of nuclear dimorphism. So far as 

 the hsemogregarines are concerned I do not think they show 

 any evidence at all of this feature (cf . Minchin and Woodcock, 

 I.e.), and therefore consider that these forms, at any rate, 

 should be kept separate.^ With regard to the malarial para- 

 sites (e.g. Plasmodium and Proteosoma), Hartmann 

 considers that these show indications of nuclear dimorphism; 

 apparently, however, the kinetonuclear element is in a more 

 " riickgebildet " condition than is the case in Halteridium. 

 Hartmann thinks, further, that these forms show other 

 evidences of a h^moflagellate ancestry, such as the presence 

 of a delicate, narrow, undulating membrane, with flagellar 

 border in the microgametes. This opinion was maintained 

 also by Schaudinn in the case of the microgametes of Hal- 

 teridium. 



Not having personally studied the finer structure of the 

 malarial parasites, I cannot say much about Hartmann's 

 opinion. If the above view is correct, as I consider it to be, 



' In a later paper on this subject, wliicli I have seen just as my MS. 

 is about to go to the press, Hartmann and Jollos (" Arch. Protistenk..' 

 xix, p. 81, 1910) have apj^arently come to the same conclusion, and 

 remove the hajmogretrarines from the Binucleata. 



