120 Dr Ru scorn's Observations on the Natural History 
us to believe, but they are two organs of station, which I shall de- 
signate by the name of claspers or hooks, ( crochets ), because they 
are analogous to the two hooks, which we observe below the 
head of the embryos of the green aquatic frog, by means of which 
those embryos attach themselves to the leaves of the lentil, and 
remain suspended. 
4tth May . — The changes of position are now more frequent. 
In that now assumed, the embryo presents the lower part of his 
head and trunk, which is white, drawing a little on green. On 
its chest, between the gills of the two sides, exactly where the 
pulsations of the heart are seen, we remark some small irregular 
blackish spots. Anterior to the two hooks or claspers, we see 
also other blackish spots, which are the junction of the two 
bands that run along the back, and were seen in the preceding 
figure. In the gills, as yet consisting only of a single filament, 
without leaflets, and as transparent as glass, we see already the 
circulation of the blood, which is very simple, and performed by 
a single curved vessel. The blood is white, and is distinctly visi- 
ble if the embryo be put on a watch-glass, and this glass be 
placed over the opening of a box, whose bottom and sides are 
blackened. The two hooks, in front of the gills, are elongated ; 
they are larger towards their extremity than at their origin, and 
are bent so that their convex side is turned upward. The sides 
of the embryo are studded with little spots of deep green, which 
form two irregular bands that extend from the fore-paws to the 
extremity of the abdomen. 
5tli May . — We now begin to see obscure traces of the eyes. 
On the two longest gills, the rudiments of two leaflets are to be 
seen. The changes of position are now made with surprising ra- 
pidity. The embryo seems greatly constrained within his little 
cell. He tries to extend himself in a straight line, and consequent- 
ly exerts continually a strong pressure against the walls of his 
envelope. The membrane, which forms the superior border of 
the tail, extends itself, diminishing in its progress even to the 
shoulders. 
6th May . — The young salamander of the natural size, just 
escaped from his envelope, as seen from above. In the progress 
of its enlargement, the embryo gradually dilates the envelope ; 
but this dilatation has its limits, and the little animal at length 
