100 Observations on the Natural History 
was, therefore, fastened on a board, the abdomen was opened, 
and its walls kept asunder by means of pins, in order to observe 
what would happen to the air-bladders. In a few minutes the 
animal began to take air into the mouth, and afterwards panted 
with a quickness always increasing for a quarter of an hour ; 
after which his pantings became weaker, and at the end of half 
an hour he died. While the proteus was thus agitated and 
panting, they watched attentively the two air-bladders, but did 
not see in them the smallest movement, which could indicate 
the entrance of air. They saw, however, that these bladders 
gradually contracted from the action of the external air ; and at 
length became corrugated to such a degree, as to resemble in 
figure two fleshy bodies, of the form and size of two grains 
of wheat. The air which entered the mouth escaped entirely 
by the branchial apertures, forming mostly minute bubbles, 
which, for some time, remained attached to the edges of those 
apertures. 
7. Of the Organs of Generation. 
The authors regret, that, under this head, their observations 
are not so complete as they could have wished ; and that some 
points relating to it are still enveloped in obscurity. 
Of the five protei dissected in the month of May, as before 
stated, there were two in whom the sexual organs were so fully 
developed, that no doubt could remain of the one being a male, 
and the other a female. In the male, the testes were attached to the 
air-bladder. To the eye they appeared to be a congeries of most 
minute globules ; but when examined under the microscope, 
their substance was nothing else than a mass of most minute 
vessels, disposed longitudinally, and extending in a serpentine 
line from one end of the testicle to the other. Towards the 
posterior part of the organ, where it had somewhat of a pyri- 
form figure, these minute vessels enlarged and separated a little 
from ecah other. Continuing the examination, they observed, 
towards the extremity of the alimentary canal, a circular ring, 
evidently formed by the internal tunic of the intestine, from 
which proceeded many longitudinal threads, which extended to 
the margin of the anus : but nothing was seen like a receptacle 
for semen, nor penis, nor vasa deferentia. A vessel seemed to 
extend from the posterior part of the testicle, and open into the 
