H. W. Acton and W. F. Harvey 
281 
India and Upper India. If any selection was brought into play, it would be 
to this extent that more Indians of the lower classes were examined than those of 
the upper. Amongst our cases some had recently suffered from malarial fever and 
others probably were suffering from helminthic diseases, if we take eosinophilia to 
be a characteristic of the latter. Thirty-five were judged to be suffering from 
anaemia as indicated by the pallor of the mucous membranes ; this point was 
always noted before any blood counts were taken ; unfortunately it was not possible 
at the time to make a haemoglobin estimation as well. Out of the total of 127 
individuals 16 came from an altitude of 3000 — 8000 feet and showed as might 
have been expected a higher count than the majority who came from the plains of 
India. 
Before giving the results of our analysis, it is necessary to give a brief account 
of the conditions that may possibly influence an examination of erythrocytes, 
as well as some of the tests that were applied by us, in order to show how these 
faults could be excluded. 
I. Expansions of glass with diminished atmospheric pressure. As Biirker* 
has conclusively shown that there is no appreciable effect produced by the expansion 
of the glass in a Thoma-Zeiss instrument as the result of the decreased atmospheric 
pressure which occurs at altitudes, this point does not concern us. 
II. Errors of technique. When commencing this investigation a number 
of trial counts were first made on ourselves and the laboratory attendants in order 
to acquire a greater technical skill and the following points were carefully attended 
to in order to avoid obtaining false results : — 
(a) The diluted blood was thoroughly mixed both at the time it was drawn 
and before blowing it out. 
(6) The glass cover slip was applied immediately before the corpuscles had 
time to settle down. Even a few seconds' delay has been shown to materially 
affect the count*. 
(c) An exact measurement of the drop was made so that when the cover-slip 
was applied the fluid extended right to the periphery and none ran over into the 
trough. No slide was examined unless Newtonian rings were seen. 
The blood was diluted 1 — 200 times with Toisson's fluid and 50 squares of 
a Thoma-Zeiss slide were counted, which meant that some 350 — 500 erythrocytes 
were counted in each individual case. 
III. Variability of observations : — 
(a) To test the degree of error of one's own observations, ten counts were 
carried out on two consecutive days on the blood of one of our laboratory 
attendants (see Fig. 1 and Table I). 
* E. Biirker, " Die Wirkungen des Hohenklimas auf das Blut," Miinchener medizinische Wochen- 
schrift, Jahrgang mi., p. 249, 1905, Feb. 7th. 
Biometrika vin 36 
