292 
Observations on Wild Rats in England 
Intestinal Protozoa. 
It is only necessary to give a list of those found, with percentage incidence. 
In 32 black rats: 
Parasite Per cent. 
Entamoeba muris Grassi 1882 ... ... 25 
Trichomonas muris Galli-Valerio 1910 81*2 
Octomitus iniestinalis Grassi 1882 ... 0-2 
Giardia muris Bensen 1907 ... ... 0-2 
Chilomastix bettcncourti Fonseca 1915... 18-6 
Eimeria fold for mis A. Scheider 1874 ... 50 
In 440 brown rats 
Parasite 
Entamoeba muris Grassi 1882 ... 
Trichomonas muris Galli-Valerio 1910 
Octomitus intestinalis Grassi 1882 
Giardia muris Bensen 1907 
Chilomastix bettcncourti Fonseca 1915... 
Eimeria falciformis A. Scheider 1874 ... 
Per cent. 
15-7 
12-7 
1-7 
6-8 
1-8 
21 
On two occasions in the black rat cysts of the E. coli type were noted. They 
are possibly the same as those found by Brug. The presence of Blastocystis 
was noted not infrequently. Some of the above findings have already been 
recorded in a paper by Stevenson (vide infra). 
Haematozoa. 
In 34 black rats 
Parasite per cent. 
Trypanosoma lewisi Evans ... 38-2 
Hepatozoon muris Balfour ... 5-9 
Grahamella joyeuxi Brumpt 1913 — 
In 444 brown rats 
per cent. 
19 
10-8 
0-2 
Dividing forms of T. lewisi , indicating an early stage of infection, were 
twice seen in the heart’s blood, and a peculiar feature of the majority of 
trypanosomes found in one rat was the presence of a small granule surrounded 
by a clear halo in the cytoplasm—adjacent and posterior to the nucleus. 
According to Wenyon this granule has not previously been noted in T. lewisi, 
and it seems worthy of record owing to the constancy of its occurrence in 
this particular instance. In some cases it was elongated, in others double, 
so it is possible that this is evidence of the division of the granule by fission. 
However, no opinion can be expressed regarding its true nature. Stained with 
Leishman it appeared of a lilac colour, very different from the deep red of the 
kinetonucleus. 
An illustrated note on “ Haemogregarines in Black Rats’’ was published 
by G. E. F. Stammers. This, it is believed, was the first record of the occurrence 
of haemogregarines in.the leucocytes of the black rat in Europe. 
