122 Dr Rusconfs Observations on the Natural History 
young tadpole, twelve days after its escape from its envelope. 
Its fore paws are now lengthened ; and, dividing at their extre- 
mity, take the form of a bicuspid tooth, the two tubercles of 
which elongate in their turn and change into two toes. The eyes 
are now disclosed, the pupil appearing of a fine black, and the 
iris of a silvery white, speckled with many colours. The yellow 
colour of the back of the little salamander is changed into a 
green : the gills, which exhibited only the first rudiments of 
leaves, are now clothed with little leaflets, in which a red blood 
circulates. The transverse depression between the eyes, which 
marked the place of the mouth, is enlarged, and, in curving it- 
self, has formed a mouth very large, the extremities of which 
extend, on the sides of the head, even to the eyes ; the head, 
which was very narrow at its back part, has enlarged greatly 
near the origin of the gills ; the two hooks have shortened by 
degrees, and almost entirely disappeared : Lastly, the body, 
which was very opake, has gradually become diaphanous, and 
to such a degree, that the observer, without injury to the life of 
the animal, is able to see the dilatations of the heart, and to exa- 
mine, through the walls of the abdominal cavity, the form and 
position of the viscera contained within it. 
These changes, however, are not the only ones which occur 
during this space of time : many others go on within, which 
have endowed the little animal with the instincts and the man- 
ners proper to its kind. Its sluggishness has vanished, and it 
displays the habits which accompany it through life. It loves 
to keep near the surface of the water, conceals itself beneath 
the leaves, or swims with surprising quickness. While floating 
tranquilly near the surface, if any little aquatic insect pass be- 
fore it, immediately it directs towards it its snout, pursues it 
slowly, and, as soon as it gets within reach, darts upon it like an 
arrow, and swallows it. In a word, the salamander, which pos- 
sessed before only a life purely organic, enjoys now a life of re- 
lation ; that is to say, an animal life. 
Fig. a , the same animal seen from above with the mi- 
croscope ; b , the same seen in profile ; c, another salamander 
of the same age (twelve days), opened below, as seen by the 
microscope; in which d indicates the arches of the gills of 
the right side, as they appear through the skin; e,. the liver; 
I 
