STUDIES ON AVIAN H.EMOPROTOZOA. 705 



my results with those obtained by Novy and McNeal tliat 

 I realise some additioual knowledo^e mig-ht have been o-ained 

 by continuing to cultivate long-er. In one case I subcultnred 

 four times at fairly slow intervals; this was done chiefly 

 with a view to seeing how long I could keep a culture of 

 the trypanosomes alive (cf. above, p. 647). Unfortunately, 

 being kept away for a few days by ill-health, I missed an 

 opportunity of examining this fourth subculture at a time 

 when the parasites Avould have been very nvimerous ; and 

 before my return an unfortunate accident had terminated 

 their career. Possibly this subculture might have shown 

 more trypaniform individuals. 



Novy and McNeal go to the length of founding two new 

 species of Trypanosoma upon the different behaviour and 

 appearance of certain of their cultural forms. In fact they 

 distinguish several types or varieties chiefly or entirely upon 

 a basis which is most inadequate and misleading, namely, on 

 a comparison of the multiplication-rosettes (really the 

 agglomeration-clusters) and the free " swarming " parasites 

 in the different cases. I only wish to point out here that, in 

 the case of both their new species, viz. T. laverani and 

 T. mesnili, the free-swarming forms which they compare 

 with the slender, trypaniform type of the other species dealt 

 with (T. avium) and contrast with the rosette-forms, are in 

 reality not trypaniform ( " spirochsetes " ) at all, but are ordi- 

 nary trypanomonad forms, which do not differ essentially from 

 those constituting the rosettes. This is perfectly obvious 

 from a comparison of their figures on Pis. 5-7. 



The matter amounts simply to this : In the case of these 

 two species, the authors have not got a development of the 

 trypaniform type at all. Many of Novy and McNeal's figures 

 of these forms, especially of T. mesnili on PL 6, are of 

 individuals which show pronounced vacuolisation, and which, 

 in my opinion, appear distinctly unhealthy; also the cluster 

 of individuals of T, laverani, reproduced in fig. 3, PI. 7, 

 I regard as partly composed of abnormal forms. In short, 

 from a comparison of the figures given of T. laverani and 



