How to obtain tt. 197 
latter being attached to their broadsides. Some have one head 
but two tails, and occasionally two fish have only one umbilical 
sac between them. A rarer occurrence is to find one possessing 
three heads, and rarer still three heads and three bodies with only 
one tail. None of these live to grow up. They usually die soon 
after the absorbtion of the “sac,” and although many persons 
have tried to rear them, no one, as far as I know, has yet 
succeeded in doing so, with the exception of an occasional cripple, 
whose body has not been very seriously deformed. I have at the 
time I write one of these moderately-deformed fish which I 
succeeded in rearing, and which has been spawned for four seasons 
in succession. The malformation does not appear to be hereditary 
in this case, and the specimen is a brook trout (Sa/mo fario). I 
had two fish amongst a batch of American trout, a few years ago, 
which had abnormally large rounded bodies. They happened to 
be a pair, and the eggs were duly taken from the one and 
impregnated with milt from the other. The young fish were care- 
fully watched, but no sign of the deformity of the parents was 
visible amongst them. 
A few alevins will probably be noticed at or near the lower 
end of the hatching box that have distended umbilical sacs, the 
part affected looking almost colourless and transparent. There is, 
in fact, a clear watery fluid, which is discharged, or partially so, on 
a puncture being made in the outer sac. The umbilical vesicle 
really consists of two sacs, one inside the other. The inner sac 
grows less as its contents are absorbed, but the outer one has not 
the same contractile power. It can be punctured, however, 
without apparently causing any pain to the fish, but the inner one 
is evidently very delicate and extremely sensitive. The proper 
function of the outer sac seems to be the protection of the inner 
one, and on the final absorption of the vesicle a part of the outer 
sac often drops off. 
The disease in question is generally known as the “dropsy” 
or “blue swelling,” and was, I believe, first so named in America 
by Seth Green. In many cases, the part affected has a slight 
bluish or bluish-grey tinge, from which it gets its name. There is 
considerable reason for assuming that it is often caused by 
using immature breeders, and it also occurs occasionally in 
