119 
and Structure of the Aquatic Salamander. 
surface, which was smooth, presents some small eminences. If 
it has not been faecundated, or has lost its prolific virtue, it en- 
larges, during the first days, the same as before, but afterwards 
changes, so as to resemble a vesicle half filled with water ; and, 
when this appearance comes on, the egg has lost its vitality. 
By the 28th, that is, by the fifth day, the embryo has become 
so much elongated, that, its envelope being short, it is obliged 
to bend itself. The parts forming the abdomen, head, and tail, 
are now easily recognized ; and, nearer its larger extremity, 
which is the head, we remark small eminences which we recog- 
nize as the rudiments of its gills and fore paws. 
By the 80th of April, all the parts above enumerated are more 
apparent. In the concave part of the embryo, and towards its 
larger extremity, we observe a small furrow which separates the 
head from the abdomen, and we see distinctly, along its convex 
border, the rudiments of the spine. 
2d May . — The embryo has now changed its position. Its 
tail has already the form of an oar. As yet, there is no appear- 
ance either of mouth or of eyes : we remark only, towards the 
extremity of the head, small blackish points, and a slight degree 
of contraction between the rudiments of the gills and those of 
the fore paws, which distinguish the head from the chest. It 
is now that the development of the embryo begins to possess in- 
terest. Hitherto the changes of form have nearly resembled 
those of a seed cast into the water ; but at this period, the ob- 
server will see the little embryo exhibit motion, array itself in col- 
ours which render it agreeable to the view, and he will also see 
the beatings of its heart. But this period, although the most 
amusing to the naturalist, is the most dangerous for the embryo ; 
for almost half the embryos, whose development the author has 
watched, have died at this period, or a little after. 
3d May . — The embryo in the last 24 hours has changed its 
position three or four times. In that it now has, it shews us all 
the upper part of its body, which is sown with little blackish 
spots, disposed longitudinally, and forming two bands, which 
extend from the head to the tail. On the side of the head, 
and before the two eminences which are the rudiments of the 
fore-paws, we observe filaments, to the number of four on each 
side. The two former are not gills, as some authors would have 
