C. Strickland 
83 
for a variable period, and the state of the T. lewisi in their alimentary 
tracts noted. (D) Further observations were made on the state of 
digestion in lice which had fed on rats infected with T. lewisi and its 
relation to the presence or absence of T. lewisi in their alimentary tracts. 
Similarly, fleas were examined from (E) infected and (F) apparently 
uninfected rats. The other organs of fleas and lice were also examined 
( G) for the possible presence of trypanosomes. 
Finally notes are appended regarding (H) the occurrence of Orithidia 
ctenophthalmi in Ctenophthalmus agyrtes. 
A. Examination of lice Haematopinus spinulosus from 
apparently uninfected rats. 
Many lice were examined, which had been taken from rats whose 
blood had been carefully examined for T. lewisi with negative results. 
It is possible that some of the 42 rats from which the lice were taken 
may have harboured T. lewisi in such small numbers that they could 
not be detected microscopically. In not one louse however could any 
developmental forms of T. lewisi be found in the gut contents either in 
fresh or in stained preparations. 
The 
following Table 
shews the 
nu mber 
of lice examined : 
Eat 
No. of lice 
Rat 
No. of lice 
Rat 
No. of lice 
Eat 
No. of lice 
Eef. No. 
examined 
Eef. No. 
examined 
Eef. No. 
examined 
Eef. No. 
examined 
3 
1 
22 
10 
43 
5 
91 B 
17 
4 
3 
26 
2 
44 
5 
68 B 
5 
5 
11 
27 
10 
46 
8 
92 \ 
6 
4 
30 
1 
55 
12 
93 l B 
8 
10 
1 
31 
2 
56 
10 
94) 
11 
1 
33 
5 
60 
2 
IX f 
8 
12 
1 
34 
6 
61 B 
13 
— 
— 
13 
1 
35 
8 
63 B 
16 
— 
— 
14 
1 
38 
5 
66 B 
16* 
— 
— 
15 
1 
39 
5 
82 B 
11 
— 
— 
16 
1 
41 
5 
83 B 
13 
— 
— 
17 
1 
42 
6 
87 B 
22 
— 
— 
12 
12 
12 
6 
27 65 133 38 
Total 42 rats, 263 lice. 
The rats marked B were from Berlin. The sign * denotes that the examination of the 
lice took place 13 hours after their removal from the rats, f IX was a tame white rat. 
Therefore 263 lice from 42 rats, apparently uninfected with T. lewisi, 
were examined, but no flagellate was found. 
6—2 
