242 Composition of Eggs. 
Perfect eggs (eufs mirs) of the Mullet, Trout, Pike, Whi- 
b.—W 
to profit by the season for spawning. We found in the ovary of 
the Plaice and Pike, and of the others, eggs entirely formed, not 
containing ichthidin at any period of their development, but very 
rich in ichthulin in their early age. Detached from the ovary, 
and free in the oviduct, they no longer showed us the least trace 
of ichthulin ; they then consist of a very albuminous liquid, con- 
taining a considerable quantity of phosphuretted fat. This quan- 
tity of albumen explains why the eggs of all these kinds of fish 
become hard by boiling. 
Eggs of Salmon.—Salmon’s eggs do not contain rectangular 
grains soluble in water. Those which we have examined were 
free in the abdominal cavity, they contained much of ichthulin 
and very little albumen. Their color, reddish yellow, is due to 
the presence of a considerable quantity of phosphuretted oil. 
Submitted to the process of boiling, they become opaque, but re- 
main always soft, even if kept a long time in boiling water. This 
is easily understood, since they have only a very slight amount 
of albumen. Their opacity is caused by the water brought into 
them, which thus stops the precipitation of the ichthulin. 
ls’ E'ggs.—The eggs or rather the ovule of the eel, taken 
in fish kept in fish-ponds are much too small to enable us to 
make researches of any extent on these curious productions of 
the organs of generation. We have been able however, to assure 
ourselves that. they contain perhaps still more fat than the eggs 
of Salmon, and they do not seem to have more albumen, for they 
do not harden by boiling. We have not been able to see in them 
the least trace of ichthidin, Our researches supply a very simple 
method of observing the eggs of the eel. It is sufficient to boil 
for a few minutes one of the ovarian lobules: then the eggs 
swell without hardening, the distended membranes become more 
apparent, and with sufficient enlargement, one easily sees the 
ovule which are hardly one or two hundredths of a millimeter. 
If, as we do not doubt, our further observations confirm those 
which we now publish, we will thus give an easy method, and a 
sure one too, to ascertain whether the female has kept its eggs 
long enough in its oviduct to perfect them, and whether they are 
in a condition to be productive. It will suffice to take a few 
from the body of the fish, to crush them on a glass-plate, and 
to add a little water. If there is no precipitate of ichthulin, the 
egg is perfect, for it only contains albumen and phosphurett 
fat. If ichthulin is precipitated, it will be*necessary to restore 
e fish to the water, and to wait awhile before proceeding Gr 
-eundation. We point this out as the most certain m 
persons who wish to try artificial breeding. 
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