704 II, M. WOODCOCK'. 



based upon the parasites present after cultivation has been 

 continued for some time, i.e. in sub-cultures of the sixth or 

 seventh generation, when the culture Avas fully developed 

 and "enormously rich in flagellates." In such cultures of a 

 trypanosome, regarded by the authors as T. avium, the 

 great majority of the trypanomonad forms were found in 

 clusters, some of whicli were large enough to be visible 

 tnacroscopically as patches in the medium. The interesting 

 point is that pai-asites in the form of " spirochfetes" were of 

 common occurrence, sometimes abundant; "spirochfete," it 

 may be as well to state, is the term applied by Novy and McXeal 

 — somewhat misleadingly — to individuals of the slender, 

 trypanifortn type, similar to those seen in my figs. 10, 126, 

 and 127.^ These trypaniform individuals were mostly free, 

 very active, and some were undergoing division. 



Hence the condition found by Novy and McXeal obviously 

 represents a much later period in the development of the 

 culture than any I have described above, and I cannot find any 

 account of the early course of the development, i.e. during 

 the first five or six days or so. The authors do not say at 

 what intervals of time their sub-cultures were made, but it is 

 evident, from the number of the "generation" given, that 

 the trypanosomes must have been cultivated for at least 

 some weeks. In the case of T. f ringillinarum, I was 

 unable to obtain any development in my cultures corre- 

 sponding to that found by Novy and McNeal in T. avium. 

 If I did not sub-culture frequently enough the parasites 

 become abnormal and degenerative, so that a preparation 

 would show nothing but altered, pseudo-herpetomonad forms 

 and so forth, and when I sub-cultured frequently the try- 

 panosomes retained, for the most part, the trypanomonad 

 phase. I never continued subculturing for so many gene- 

 rations as Novy and McNeal did ; it is only since I have 

 come to study carefully my preparations and to compare 



^ Althongli in one or two cases these parasites show indications of an 

 extended nucleus, in no case is a definite ladder-like appearance figured 

 or described. 



