326 DR DAVY’S OBSERVATIONS ON THE CHARR. 
projecting, resembling fins, and were in constant motion over the branchial arches, 
in which the blood corpuscles were to be seen circulating in looped vessels. 
On the 4th of February, it is noticed that the fish were acquiring colour, dark 
colouring matter being deposited in stelliform specks; that the embryonic fin was 
diminishing, and that the adipose fin was beginning to appear, marked by a slight 
elevation. 
On the 14th of the same month, they were found to have increased to about 
‘8 of an inch in length, and the yolk to have diminished to *2 of an inch, and to 
have become narrower. 
On the 22d, the water in which they were kept was frozen over: they were 
seen swimming actively under the ice, and restlessly, as if in search of a passage 
to deeper and less cold water. 
On the 13th of March, the dorsal fin was almost apart, the other fins advan- 
cing, the single one receding from absorption; the tail still rounded; the abdo- 
minal integument extending over the diminishing yolk, but not yet entirely 
covering it. 
One died on the 18th of this month; the others on the following day. In 
these there was an appearance of sooty matter about the gills, which probably 
was the cause of their death, by obstructing respiration. One of them, weighed, 
was found to be little more than half the original weight of the egg; merely 
wiped, it was equal to ‘58 of a grain; thoroughly dried, at a temperature of 100, 
it was reduced to ‘16 of a grain. From the time of their hatching to that of their. 
death, I am not aware that they had taken any food other than that provided for 
them by nature in the attached yolk, a period of sixty and sixty-one days. Pro- 
bably had they been favourably situated, where they could have found suitable 
food in the water, their growth would have been more rapid. One taken from 
the breeding-boxes on ‘the 22d of March, hatched about the same time as the 
preceding, viz., the 17th of January, and when, consequently, about sixty-five 
days old, may be adduced in proof; premising that, from the manner in which 
the boxes were supplied with water, and their being shaded with trees, and some 
aquatic plants having been introduced, brought from the bed of the Brathay—that 
part of the river where the charr is known to spawn—there was probably no want 
of the proper food of the young fish, minute insects and infusorial animalcules, 
traces of which, indeed, were detected in its excrements, when seen under the 
microscope using a high power. The young fish of the age mentioned was perfect 
in its form. The embryonic fin had entirely disappeared, with the exception of 
a slight vestige of it between the anal and the abdominal fins. All the permanent 
fins had become distinct, even the adipose, though it was rather more extended 
and less elevated than in the full-grown fish. The caudal had lost its rounded 
form, and had become not forked but square. No vestige remained externally of 
the yolk-vesicle, the abdomen being entirely closed, covered uniformly with a 

