226 
H. M. WOODCOCK. 
sullies. I naturally coucluded that both Berliner and I myself 
had seen the same nuclear condition as that which I had con- 
sidered to represent nuclear dimorphism when found, on 
Giemsa-stained smears. I remember putting aside these wet 
preparations of Halteridium until a convenient opportunity 
for their detailed study should come along, with the thought 
that there was at least one point which was extremely diffi- 
cult to determine from an iron-haematoxylin preparation, 
namely whether a particular individual was of male or female 
sex ; it appeared to me as if, notwithstanding the well-marked 
distinction between the male and female nucleus after staining 
with Gieinsa, the nucleus of both kinds of gametocyte was 
really of essentially the same form and structure, and the 
same view seemed to have been taken by Berliner, since he 
did not distinguish the sex. 
Having found, however, since I began to study the cytology 
ofLeucocytozoon ziemanni, that there is a constant differ- 
ence between the nucleus of the male and female gametocytes 
respectively when stained by iron-haematoxylin just as in 
the case when stained with Gieinsa, it was necessary to 
return to the Halteridium and try and .settle the question 
as regards that form. Fortunately, I have recently obtained 
another chaffinch with a fairly good infection of H. fringil lae, 
in which most of the parasites are approximating to the adult 
condition and whose sex can therefore be readily dis- 
tinguished. This time I at once made some iron-haematoxylin 
preparations, the examination of which happily enlightened 
me upon the whole question, in quite as great a measure as 
the study of Giemsa-stained ones helped to lead me astray in 
the first place. With the knowledge thus gained, I turned 
once more to my preparations of H. noctuae, and have now 
been able to ascertain that the nuclear structure here also 
shows the same constant differences in the male and female 
forms. 
In figs. 28, 29 are seen male gametocytes of H. fringil lae, 
and in figs. 30, 31 the corresponding forms of H. noctuae. 
Both the red blood-corpuscles and the adult individuals of 
