Gr. F. Petrie and C. R, Avari 
319 
It would seem, however, that this relationship is not so striking as in the 
case of the temperature. 
TABLE VI. 
Giving mean monthly figures for temperature and humidity (saturation = 100) 
for Bombay and Lahore , Punjab*, 1905—1906. 
Mean temperature. 
Mean humidity. 
Bombay 
Lahore 
Bombay 
Lahore 
November 1905 
80 
— 
67 
_ 
December 
75 
-57 
65 
89 
January 1906 
73 
54 
07 
84 
February 
73 
57 
67 
88 
March 
76 
65 
73 
81 
April 
80 
76 
76 
51 
May 
85 
88 
73 
39 
June 
84 
94 
81 
57 
July 
81 
93 
87 
69 
August 
81 
89 
87 
74 
September 
81 
84 
82 
77 
October 
83 
77 
75 
67 
November 
— 
09 
— 
78 
* The 2 Punjab villages, the rats of which were examined for the Leucocytozoon, 
are situated only a few miles from Lahore. 
It has been shown above that in the case of T. lewisi in rats definite 
seasonal variations in prevalence exist. Before concluding this paper 
another example may be given of a “ chronic ” protozoal infection in 
rats showing similar seasonal variations. The parasite to which we 
refer is the Leucocytozoon, which was commonly observed by the Plague 
Research Commission (1907) in the rats (M. rattus) of two Punjab 
villages. A daily record was kept of the number of rats, in the spleen 
of which this parasite was found. Altogether during a year’s investi¬ 
gation 9499 rats were searched for the parasite by the Commission and 
1309 rats were found infected, a percentage for the entire year of 13'8. 
We have represented graphically in Chart VI (see also Table IV) 
the monthly percentage figures of infected animals published in the 
Commission’s reports. It is apparent that the prevalence curve of the 
Leucocytozoon bears a general resemblance to the curves representing 
the prevalence of T. lewisi in Bombay. It will be noted that in this 
