524. E. A. MINCGHIN AND H. B. FANTHAM. 
the photo-micrograph given us (Pl. 30), which shows the 
general appearance of a section under a low power. The 
growth, which has been compared by O’Kinealy to a straw- 
berry, raspberry, or arbutus-berry, has the surface much 
folded and covered everywhere by stratified epithelium. In 
places the folds form deep “crypt-like involutions,” as 
Vaughan has termed them (1), into which the epithelium 
extends. Below the epithelium is a stroma of connective 
tissue in which are lodged the parasitic cysts. Some cysts . 
also occur deep down in the epithelium. The cysts vary very 
much in size, as Vaughan has already pointed out (1), and 
also in form. Usually nearly circular in outline, they may 
be oval or elongated, almost tubular in form (fig. 8). The 
cyst-wall is hyaline, of considerable thickness, and showing 
no trace of cell-structure. Its outer contour-line is very dis- 
tinct, but its inner limit is not so sharply defined. The thick- 
ness of the cyst-wall in different cysts varies considerably. 
We have nothing to add to the description of the cyst-wall 
given by its discoverers, except as regards two points. In 
the first place, it is described by Vaughan as showing a 
concentric striation, but it appears to us to be perfectly 
homogeneous and structureless, and we regard the apparent 
concentric striation which may be observed occasionally when 
an oblique section of the cyst-wall is focussed up and down, 
as due to diffraction phenomena. In preparations stained 
with gentian violet and orange the cyst-wall takes up the 
gentian violet, and its extent and structureless character 
then become quite evident. With Delafield’s hematoxylin 
also the cyst-wall stains pale blue, with slight concentration 
and darkening of colour on the inner side. Heidenhain’s iron 
hematoxylin also shows up the cyst-wall very distinctly. 
Secondly, we are unable to confirm O’Kinealy’s statement (2) 
as to the presence of ‘fa pore in the cyst-wall through 
which the bodies escaped into the surrounding tissues.” We 
have not found such a pore in any cyst that has come under 
our observation. 
We come now to the most important feature of the parasite, 
