Davaineid Cestode from a Wallaby. 603 
solution for about a quarter of an hour, after which they were 
washed for a few hours in running water, and were then 
placed in 70 °/, alcohol to which a few drops of iodine 
solution were added. The addition of iodine was continued 
— until the colour was permanent, after which it was poured 
_ off and replaced by 70 °/, aleohol, in which the animals were 
permanently preserved. ‘The rest of the worms were placed 
in tap-water, and allowed to remain in it until they were 
completely relaxed and dead. ‘They were then dropped into 
a preserving fluid, consisting of equal parts of pure glycerine, 
70 °/, alcohol, and distilled water, and as this fluid became 
turbid it was replaced by fresh preservative. This _pre- 
servative tends to keep the worms soft, and such specimens, 
after the excess of glycerine has been washed out by distilled 
water, are found to stain very well with Ehrlich’s acid 
hematoxylin, 
(b) Study.—Serial transverse and horizontal sections, 
7 thick, were cut of mature and ripe proglottids ; these 
were stained with Ehrlich’s acid hematoxylin with eosin as 
a counter stain. For the preparation of whole mounts, 
weak Ehrlich’s acid hematoxylin was used, and the worms 
were allowed to stain overnight; they were then differ- 
eutiated in acid alcohol and eventually blued in tap-water ; 
after slightly pressing them between two microscopic slides 
and dehydrating them in this coudition, the worms were 
finally mounted in Canada balsam. Acetic alum hematin 
and acetic acid carmine were also tried, but these stains did 
not give satisfactory results. 
ExtTeRNAL CHARACTERS. 
(a) Haternal Appearance.—The specimens vary in length 
from 24 cms. to 35 cms. Anteriorly the body is very much 
attenuated, but posteriorly it gradually increases until about 
halfway down its length; here the maximum breadth— 
about 4 mm.—is attained; more posteriorly the strobila 
again becomes narrowed, so that at its hind end it is only 
about 1 mm. broad. 
The anterior segments are very narrow, but they become 
slightly longer posteriorly, and in the middle of the body 
they are about one-tenth as long as they are broad. Towards 
the end of the body the segments decrease in breadth and 
increase in length, so that the terminal segments are about 
twice as long as they are broad, and somewhat barrel-shaped. 
The posterior lateral margin of each segment projects 
slightly over the segment following: this is more marked 
- 39* 
