E. Hindle 
425 
Observations on the living parasites. 
As in the case of T. brucei (Nuttall, 1910), the trypanosomes shewed 
increasingly active movements up to 1 —12 hrs. after the injection, but 
after this their motion gradually diminished until after 5 hrs. only the 
flagellum moved slowly. Shortly after treatment the trypanosomes 
appeared more granular and opaque, and the number of granules could 
be seen increasing, until finally the parasites broke up into fragments 
which were ingested by the leucocytes. The short stumpy forms are 
the last to disappear from the blood, and therefore the percentage of 
them gradually increases as the other forms die off. 
The number of parasites in the peripheral circulation begins to 
diminish immediately after the injection of arsenophenylglycin, as is 
shewn in the following table. 
Time 
Treated Rat A. 
Number of parasites 
9.30 a.m. 
80 per micr. field. 
10.00 a.m. 
Eat, weight 100 gms., inj. subcut. with 1 c.c. 
10.30 a.m. 
of 2 “/o sot of arsenophenylglycin. 
75 
11.30 a.m. 
... 
65 
12.30 a.m. 
50 
1.30 p.m. 
20 
2.30 p.m. 
1 to 10 fields. 
3.30 p.m. 
1 to film. 
4.30 p.m. 
negative. 
In this 
respect, therefore, the behaviour 
of the parasites 
treatment with arsenophenylglycin differs from that after atoxyl, as in 
the latter case the number of trypanosomes in the peripheral circulation 
usually increases shortly after the injection and only subsequently 
diminishes. In both cases, however, the first effect of the drug is to 
cause an increased activity in the trypanosomes and afterwards granular 
degeneration. The number of leucocytes in the blood increases after 
an injection of arsenophenylglycin ; the same phenomenon has also been 
observed after treatment with atoxyl. 
Observations on the living parasites stained in vitro. 
A certain number of observations were made on the living parasites 
stained with neutral-red. It was found most convenient simply to 
run under the edge of a coverslip preparation of the blood a drop of 
