STUDIES ON AVIAN H^MOPROTOZOA. 659 



not able to see it iu the peripheral blood at all during the 

 first five months of the year, although in two cases I knew 

 by means of cultures that the birds were infected. During 

 the early autumn, however, I was able to find it in smears from 

 a very young bird, which had probably not been long 

 infected. Tlie number of parasites on a fair-sized film 

 varied from six to ten in September, but only from four to 

 eio:ht in films made in October. 



Principal Habitat. — In general, the trypanosomes are 

 most numerous in the bone-marrow; this is certainly their 

 principal habitat. Two or three parasites can usually be 

 found in a fresh cover-slip preparation from one of the long 

 bones of an infected bird. But even here, at times, consider- 

 able search is necessary,^ since the parasites are apt to be 

 hidden by clumps of leucocytes, ery throblasts, etc. However, 

 there is generally no difficulty in finding the trypanosomes 

 in a carefully made smear of a small, teased-up fragment of 

 bone-marrow. Thus, when the chaffinch above alluded to 

 was killed, some of the smears from the bone-marrow con- 

 tained twenty trypanosomes or more. 



Artificial Infection. — Only in a couple of instances up 

 to the present have I had the pleasure of finding trypano- 

 somes at all plentiful in the peripheral circulation. One of 

 these cases, at any rate, was certainly the result of success- 

 ful inoculation. This was a chaffinch which was infected 

 with a culture of the form from the redpoll. Examined 

 previously, no parasites had been found in this bird. On 

 December 19th it was inoculated inti'a-peritoneally with a 

 fifteen-day culture. On December 21st, twelve days later, 

 examination of the blood showed at least five trypanosomes 

 in two fresh cover-slip preparations, which were not ex- 

 haustively searched; and permanent smears made at the 

 same time proved to contain quite a considerable number of 

 parasites — twenty to twenty-five or more on a good-sized 



^ Certainly in one instance, wliere I failed to find any parasites in a 

 careful search of the bone-marrow, the trypanosomes subsequently 

 appeared in a culture taken from this organ. 



VOL. 55, PART 4. NEW SERIES. • 44 



