660 H. M. WOODCOCK. 



film. On New Year's Day also, two parasites were found in 

 a living preparation without much difficulty. When next 

 examined, however, on January 10th, only one trypanosome 

 was seen in two cover-slip preparations, which were 

 thoroughly searched; this indicated a marked diminution in 

 numbers. And in one permanent smear taken at the same 

 time I could not find a trypanosome at all. This bird was 

 not looked at again until the beginning of February, when no 

 trypanosomes were seen in a living prepai-ation. Neverthe- 

 less, the parasites were still present, for a tube inoculated 

 subsequently developed a culture; evidently the parasites 

 had by this time diminished in number to their customary 

 scantiness. Unfortunately, this chaffinch accidentally escaped 

 soon afterwards, flying away through an open window. 



A Strong "Mixed" Infection. — I have left to the last 

 a consideration of my most interesting case. On March 20th 

 I inoculated a chaffinch with a seven-day culture of the 

 chaffinch form. Three good (i . e. sterile) tubes had been 

 inoculated from this bird previously, and had not developed 

 any parasites. Hence I was practically certain that there 

 were no trypanosomes present in this bird. Examination of 

 the blood at intervals from March 26th until April ;3rd, that 

 is, until fourteen days had elapsed since inoculation, proved 

 negative, no cover-slip preparations showing any parasites, 

 so that I was very doubtful whether the inoculation had been 

 successful. About three weeks afterwards the bird was 

 asrain examined with a like result, but to make the matter 

 certain, a tube (the first)^ was then taken. To my surprise 

 this developed a culture, the presence of the trypanosomes 

 being thus proved, although I had never seen them in the 

 fresh blood. I propose to leave aside, for the present, the 

 question of whence these ti'ypanosomes had come. 



* I had not made a culture on the occasions of the earlier examina- 

 tions, thinking that if the inoculation had Ijeen successful the parasites 

 would have been readily obsei-ved in the circulation, as in the other 

 instance described. 



