C. Dobell and M. W. Jepps 
337 
about 12-14 jU.; whilst Case B. 1 was merely noted as having many large 
cysts 15/r or more in diameter^. 
Attention must here be drawn to the character of the curves obtained 
from each of our series of measurements. Inspection of Figs. 1-4 will 
convince the reader, we believe, that all the curves are of essentially the 
same form. They are unimodal, each with a single apex, and, like a 
normal curve of error, approximately symmetrical about the mode. 
With the exception of one curve (saline) shown in Fig. 2—which we have 
already discussed and concluded to be abnormal—we have up to the 
present obtained no curves which are not conformable to this type. We 
conclude from these findings that, in each case so far described, we are 
deahng with a single pure race of E. histolytica producing cysts whose 
average diameter is constant, and which show merely those variations 
in size from the mean which are to be expected in any biological species 
or strain displaying the usual degree of variability. 
For certain other cases, however, a different type of curve was ob¬ 
tained. Three such cases are shown in graphic form in Figs. 5^, 6 and 7; 
the actual measurements upon which these curves are based being given 
It is just possible that it may occur to some reader that the large size of many of the 
cysts in the infections E. 42 and B. 1 is due to the inclusion of cysts of E. coli in the series 
measured. We would therefore state explicitly that neither of these cases is infected with 
this species, and that cysts containing more than four nuclei have never been found in the 
stools of either. 
^ The cysts from this case (E. 130) were stained with Weigert’s iron-haematoxylin— 
not with haemalum as were the others. 
