724 H. M. WOODCOCK. 



as being about to pass actually into little active trypanosomes, 

 in a manner similar to that described by Scliaudinn, that is 

 to say, by getting- rid of a portion of the cytoplasm con- 

 taining the effete pigment-grains and by the development of 

 a flagellum, the proximal, attached part of which constituted 

 the flagellar border of an undulating membrane. In spite of 

 much searching, I have not succeeded in finding any further 

 stages in this developmental change. I cannot suggest any 

 other satisfactory explanation of this peculiar structure, how- 

 ever, and I still continue to think it has some connection with 

 a flagellar development, as will be seen in a subsequent 

 paragraph. 



The halteridial parasites of small or intermediate size, 

 which I have now found to occur occasionally free from the 

 corpuscles (cf. p.663), seem to be quite ordinary in character 

 and show nothing unusual. I have seen nothing at all in 

 these to indicate that they undergo any transition to a 

 trypaniform phase. The same observation applies equally, I 

 am sorry to have to say, to Halteridium noctuas, where, 

 in one or two cases of very strong infection, I have found 

 free individuals, of varying size, to be quite numerous. 



As I pointed out in my note, the possession by an intra- 

 cellular parasite of nuclear dimorphism, in the sense in which 

 I have used this term, is very significant and important 

 evidence in favour of a flagellate affinity or connection of the 

 parasite exhibiting this feature. Indeed, on a priori gi-ounds, 

 the undeniable occurrence of this distinctive character in 

 Halteridium is, even regarded by itself, a very weighty 

 argument in support of Schaudinn's view of the ontogenetic 

 connection of this intra-cellular form with a trypanosome. 

 When, in addition, the other evidential points to which I 

 alluded were taken into account, such as the occurrence, 

 now and then, of individuals attempting (as I consider) to 

 develop a flagellum, and the occurrence of very small trypano- 

 somes at the same time, Avhich were no larger than the full- 

 grown Halteridia, the most reasonable conclusion did appear 

 to be that the two forms of parasite were indeed connected. 



