Miscellaneous. 163 
sacs, tore it out of the tentacle, and swallowed it. Several other 
similar experiments gaye the same result. The most interesting 
was one in which, a mealworm having been placed side by side 
with a Succinea, the author saw a blackcap seize first the Leuco- 
chloridium and afterwards the mealworm. In all these experiments 
it was observable that the bird, after having seized the Leuco- 
chloridium and torn it out with a single strike of the bill, 
swallowed it, sometimes immediately, sometimes only after striking 
it several times against the floor of its cage or the perch, thus 
behaving exactly as the insectivorous birds do with their ordinary 
food. 
From the success of these first experiments Dr. Zeller had great 
hopes of being able to confirm his hypothesis by the autopsy of the 
birds. So his disappointment was great when he did not find a 
single Distomum macrostomum in three redbreasts and a blackcap 
which he dissected some weeks after he had seen them swallow 
the Leucochloridia. He then questioned whether the larvee of Dis- 
tomum contained in the Leucochloridia had been quite mature, or 
whether, perhaps, the artificial nourishment of the birds might not 
have exercised an injurious influence upon the parasites. In order 
to avoid these causes of failure he made fresh experiments, employ- 
ing this time some Succinew which had been kept for a long time 
in captivity, and containing Distomum-larve, the development of 
which could not but be sufficiently advanced ; and at the same time, 
instead of cage-birds, he made use of young birds in a free state, 
but still in the nest. These birds were shut up with their nests in 
small cages, and left in a place where they could be fed by their 
parents. 
Three series of experiments, made under these conditions, upon 
whitethroats (Curruca garrula), blackeaps, and wagtails were 
crowned with full success. The Distoma were fixed in the rectum 
in great numbers and very lively ; their reproductive organs pre- 
sented a state of development more or less advanced, according to 
the length of time they had remained in the intestinal canal of their 
host. In some of them the oviducts were to be seen filled with ova, 
some of which even were already of an intense yellow colour. The 
development of the larva of Distomum macrostomum into the adult 
animal is very rapid; and the production of the ova seems to com- 
mence within six days after the migration. 
Dr. Zeller completes his memoir with some observations on the 
species allied to D. macrostomum, and upon the hosts which furnish 
nourishment for these different species of Distomuwm. He con- 
siders that Diesing was wrong in combining with D. macrostomum 
the D. erraticum and D. ringens of Rudolphi. On the other hand, 
he convinced himself that D. mesostomum, Rud., which occurs in the 
song-thrush, the grosbeak, the bullfinch, and the greenfinch, is 
quite distinct from D. macrostomwn. But D. holostomum, Rud., 
from the water-rails and the common water-hen, which M. von 
Siebold supposed to be the adult form of the larva of Leucochlori- 
