62 
C. H. MARTIN AND MURIEL ROBERTSON. 
from the wall, and, at any rate in the fowl, most of the 
division stages occur in the actual crypts of the wall itself. 
The method we adopted in the examination of our fowls 
was to open up the caecum, and after cutting away a portion 
of the caecal wall to smear it on the surface of a clean cover- 
slip. The smears were then plunged into a tube containing 
either strong* Flemming or corrosive acetic. 
Both fixatives gave excellent results. The Flemming smears 
were washed out, according to the method recommended by 
Overton, with a solution of a little hydrogen peroxide in 
70 per cent, alcohol, while the corrosive smears were washed 
out with a weak iodine solution in 70 per cent, alcohol. 
The most serviceable general stains were found to be dilute 
acid Mayer’s haem alum counter-stained by eosin, though 
in addition we made use of a large number of preparations 
with other stains, e. g. iron-haematoxylin, Gfiemsa, Twort, 
Delafield’s haematoxylin, borax carmine, alum carmine, 
safranin, methyl green; and as counter-stains we also found 
orange Gf., Licht-griin and picric acid, and picric acid alone, 
valuable. 
Sections were found only to be of value as v an indication 
of the distribution of the parasites in the gut. As has already 
been stated, the great advantage which the fowl offered over 
all other animals for the study of these gut parasites seemed 
to us to lie not only in the great ease with which it was 
possible to obtain uninfected individuals from eggs hatched 
in incubators, but also in the fact that it was quite easy to 
keep the young chicks free from all animal infection for 
weeks. As far as we are aware none of the other animals 
which has hitherto been used for work on similar parasites, 
viz. the frog, lizard, mouse, man, is so easily handled ; since, 
in the first place, with the fowl it is quite easy with suitable 
incubators to get a practically unlimited supply of uninfected 
material almost throughout the year; secondly, the animals 
can be easily kept in a healthy condition on sterilised food ; 
thirdly, the caeca in young chicks are just a convenient size 
to handle, and they are not too big to prevent the fixed 
