STUDIES ON AVIAN H.^<:M0PR0T0Z0A. 643 



to study first the parasites of the "little owl" itself. In 

 spite of all my efforts, however, I could not obtain a supply 

 of these birds here at home, so that I was obliged to turn 

 my attention to other birds. Kecent observations have 

 shown that many kinds of birds hai'bour trypanosomes, and 

 it is probable that their infection with these parasites is 

 fairly widespread in nature (cf., for instance, the numerous 

 American species which Novy and McNeal found to be 

 infected). The only worker, to ray knowledge, who has pub- 

 lished any notes relating to the occurrence of avian 

 trypanosomes here in England is Petrie (21), who 

 observed the parasites in the blackbird, swallow, house- 

 mai'tin, song-thrush, chaffinch, and yellow-hammer ; he 

 failed to find them in the crow, sparrow, stai-liug, or 

 jackdaw. 



Had it been my object to find trypanosomes in as many 

 different birds as possible and to content myself with 

 noting their presence, it Avould have sufficed to shoot 

 various kinds of wild birds and examine them at once. This 

 habit of describing and naming trypanosomes from one or 

 two casual observations is unfortunately far too prevalent ; 

 it is one which adds little or nothing to our knowledge of the 

 i-eally essential points on which light is needed. For the 

 purposes of my investigation I felt it was best to restrict 

 myself to birds which could be obtained without much 

 difficulty, and which were hardy and would live well in 

 captivity. Hence, with a few exceptions at the commence- 

 ment of the work, when I was endeavouring to 'May a 

 course" as it were, I have used small native cage-birds, 

 obtained from various dealers. Mentioning the exceptions 

 first of all, in order to give a complete list, I began with 

 some Java sparrows (Pad da oryzivora), from which host a 

 trypanosome, T. paddae, has been described by Thiroux. 

 But after spending some time fruitlessly in attempts to find 

 this parasite, which was not present, and my limited supply 

 of these birds giving out, I relinquished the search. In spite 

 of great efforts to trap common birds, the only result was a 



VOL. 55, PART 4. NEW SERIES. 43 



