STUDIES ON AVIAN H^MOPROTOZOA. 663 



— in spite of much searching — were four or five instances in 

 which a special kind of individual, with peculiar featui-es, 

 was found free in the plasma. Having been led, however, 

 as a result of my observations at Rovigno, to again examine 

 very carefully certain of my pi-eparations made at night, I 

 have now found here and there a few individuals of small or 

 intermediate size, and apparently of normal appearance, free 

 in the blood. It is noteworthy that these free individuals 

 have been seen only in smears from the peripheral blood, 

 and not, for instance, in preparations from the liver, where 

 the parasites are most numerous. Hence I do not think 

 that the first impression I formed, namely, that theHalteridia 

 do not leave the blood-corpuscle in the course of their 

 growth, can be sustained. 



Occurrence of the Leucocytozoon . — The new 

 leucocytozoon which I have observed occurred in three 

 chaffinches. In two it was very scanty, only one or two 

 isolated individuals having been noticed, and they were 

 small. In one bird, however, which happened to be that 

 which was successfully inoculated with Trypanosomes from 

 the redpoll (see above, p. 659), the Leucocytozoon is not 

 at all infrequent. The parasites are nothing like so 

 numerous as the Halteridia are in the case just described, 

 but there are certainly as many or more Leucocytozoa than 

 there are trypanosomes on any smear. On one film more 

 than twenty-five have been marked, and the slide has not 

 been exhaustively searched for all the minute forms. 

 Unfortunately, I did not detect this parasite in living, 

 cover-slip preparations. For one thing, I was examining 

 the chaffinch in which it occurred for Trypanosomes, which 

 can be readily seen ; further, as this species does not 

 produce the characteristic spindle-like appearance of the host- 

 cell, as in the case of nearly all other Leucocytozoa so far 

 described, there was nothing about the parasites to catch 



obviously been accidentally set free from a ruptured corpuscle in making 

 the preparation, such as are occasionally met with. 



