12 Experiments on the Development of the Liver-Jiuke. 
hepatica. For, calling the small black slug upon the distribution 
of which I have, following Schrenk and Middendorff, just been 
writing, " Avion ater^^ 1 have the example and authority of 
Forbes and Hanlej, and I think that of Gerstfeldt. But now, 
following Schrenk more closely, I should call it Avion hovtensis, 
and should wish to be understood to be of opinion that it will — 
as I hope, by means of experiments now being carried on in my 
laboratory by Mr. A. P. Thomas — be ultimately shown that 
the smaller of our two British Arions really is one at least of 
the hosts infested by the sheep-fluke, Fasciola hepatica. 
As regards the distribution of the Fasciola hepatica in 
northern regions we have the authority of Leuckart, ' Die 
Menschlichen Parasiten,' i. p. 531, 18C3, for saying that it is 
found in Greenland and North America ; and the same ex- 
cellent authority quotes, I.e., ii. p. 870, 187(3, Krabbe to the 
effect that it is not found in Iceland. The last statement is 
confirmed by Jonsson in ' Deutsche Zeitschrift fiir Thier- 
medicin und vergleichende Pathologic,' Bd. v. Heft vi. 1879, 
p. 413, in the words " Leberegeln kommen in Island nicht 
vor." I wish to add that there is no mention of the disease 
which Fasciola hepatica causes in Olafsen's and Povelsen's two 
volumes of ' Travels in Iceland,' though the diseases of sheep are 
repeatedly treated of by those authors.* And a similar remark 
may be made as to Siberia ; neither Middendorff, nor Radde, 
nor the great Pallas, treating as they do so exhaustively of 
the natural history of that region, ever within my knowledge 
make any allusion to the existence there of Fasciola hepatica as 
a cause of sheep disease. As regards, however, the existence of 
this animal and of the sheep-rot in Greenland, as testified by 
Leuckart, I wish to lay alongside of it the following state- 
ment from the English translation of Rink's 'Greenland' already 
referred to, and edited by Dr. Robert Brown in 1877. There, 
p. 97, it is stated that about the year 1855 there were in the 
whole of Greenland only from 30 to 40 cows, 100 goats, and 
20 sheep, and that this handful of cattle were located at Julians- 
haab, on the west coast. A statement to the same effect is given 
by Dr. Brown himself in the ' Manual of Arctic Instruction,' 
1875, p. 27. Surely if the rot still exists in Greenland, and has 
not shared the fate of so many other forms of life which have 
finally left its inhospitable shores, we have in Julianshaab a 
simple case and a circumscribed area wherein to prosecute 
research. 
If the presence of Fasciola hepatica in an isolated locality — 
* See German translation published in 1794, i. pp. 112-280; ii. pp. 46, 198, 
199. 
