192 
POPULAR SCIENCE REVIEW. 
stance becomes homogeneous, and the nuclei become spherical, and soon 
acquire the value of complete cells. They are surrounded by a layer of 
protoplasm, enveloped by a membrane. In this protoplasm four or five 
spherical granules make their appearance, and soon attain the size of the 
nucleus, producing a mulberry-like mass of five or six grains enclosed in a 
common envelope. The enveloping membrane disappears and the grains 
separate, and again multiply by a process analogous to that already described. 
As these embryonic cells increase in number the contractile substance is 
absorbed, and at a more advanced stage the place originally occupied by the 
muscular bundle shows only a mas3 of embryonic cells engaged in constant 
proliferation. 
In the second mode the sarcolemma also disappears, and the muscular 
nuclei show a very distinct envelope presenting a double contour. They still 
retain their original lenticular form, and their centre is occupied by a small 
spherule composed of fine granules. These granules become fewer and 
fewer ; they separate and finally disappear, when the nucleus is represented 
only by its empty envelope. While these changes are going on the con- 
tractile substance gradually disappears, by a sort of melting away, but 
without altering the general form of the bundle, finally producing a colour- 
less, very finely granular substance, containing the original nuclei in any 
stage of the degeneration just described. 
Habits of Callichthys faciatus. — M. Carbonnier records some curious par- 
ticulars of the habits of Callichthys faciatus — a Siluroid fish from the rivers 
of South America. His observations are made upon specimens from the 
Rio de la Plata, living in his aquarium, and relate chiefly to the reproduction 
of the fish. He states that when about to deposit her eggs the female 
brings together the ventral fins in such a manner as to form a sort of pouch, 
in which the fertilizing elements furnished by the male fish are received and 
retained. The ovarian orifice is at the bottom of this sac, and through it 
some five or six eggs are extruded into the sac, where they are of course 
surrounded by a fluid charged with spermatozoids. To secure impregnation 
the female retains the eggs in the pouch formed by the ventral fins for a 
short time before finally depositing them. For the latter purpose she selects 
a spot, usually well illuminated, which she cleans with her mouth from all 
adhering vegetation, or other inconvenient objects, and then applying her 
abdomen to the place, opens the sac and attaches the eggs, which adhere by 
means of the viscosity with which they are endued. The same process is 
repeated until all the eggs — numbering about 250 for each female — have 
been laid. The young fish are developed and able to swim about in from 
twelve to thirteen days; but their further development is comparatively 
slow, as they do not appear to become adults until two years after hatching. 
A singular fact mentioned by M. Carbonnier is the change that has taken 
place with his CaUichthyes in the season of oviposition since their transpor- 
tation to Europe. In the Kio de la Plata the eggs are laid in October and 
November. After being in Europe for a year the South American speci- 
mens bred in August and September, 1878, and the young fish thus pro- 
duced have their eggs in the month of June. This would seem to indicate 
an adaptation to the change of climate to which the fish have been sub- 
jected, the seasons in South America being the reverse of those in Europe 
( Comptes Itendus, G December, 1880). 
