A. C. Coles 
25 
thicker in the middle and tapering towards both extremities. As a full 
description of this trypanosome has been given previously (1913) I will 
merely add the measurements which were as follows. 
Total length, 98/a; length of body, 88/r; free flagellum, 10 yu.; 
distance from the posterior extremity to kinetonucleus, 37 /a, and to the 
centre of the nucleus, 44 yu.; distance between trophonucleus and kineto¬ 
nucleus, 5 5 fi ; diameter of body at trophonucleus, 6 yu,, together with the 
undulating membrane, 9'5 ya. 
TRYPANOSOMES OF BIRDS. 
During the course of a somewhat extensive examination of the 
blood of birds I have met with trypanosomes in the blackbird (Merula 
vulgaris), the thrush {Tardus musicus) and the jay {Garrulus 
glandarius). In 1904 I met with one trypanosome in a blackbird which 
I have described elsewhere (1906). In the thrush both large and 
small trypanosomes were found, in the blackbird and jay otdy the 
large variety has so fax been seen. I have met with about 150 
trypanosomes in blackbirds, about 100 in thrushes and about 40 in 
the jay. 
Trypanosomes of the Blackbird. 
These vary very much in numbers. In a cock bird killed July 10,1911 
they were the most numerous; 44 well spread blood, films were 
examined over an area of a f incli coverglass and 40 of these were found 
to contain 124 parasites, four films proved negative, the average 
number of trypanosomes found on each film was about three and the 
largest number seen on a single film was 13. Several films of bone 
marrow were examined but with negative results, whilst a single 
parasite was found in a lung and liver smear. The trypano.somes in 
this bird were associated with the round form of Leucocytozoon. 
The trypanosomes may'for convenience of description be divided 
into two classes which I have termed the Fusiform and the Piriform in 
outline. Although these may merely represent different aspects of the 
same organism, they certainly have some distinctive features. The 
fusiform or spindle-shaped parasites stain a much deeper blue colour, 
they almost invariably show myonemes or contractile fibrils, they are 
longer, narrower, and possess a longer flagellum. The piriform are 
roughly pear-shaped, they stain a much lighter colour, they are shorter 
and broader, never show myonemes, but the protoplasm is generally 
somewhat granular. 
