130 Mr. Davy’s observations on the 
venom-follicles are situated, and where there is a plexus of 
veins of great size, as if intended for a reservoir of blood. 
This last-mentioned peculiarity of structure, and the situa- 
tion of it, corresponding to the site of the gills of the tadpole, 
would seem to indicate, that the sub-cutaneous distribution 
of the second branch of the pulmonary artery, may aid the 
lungs farther in their office by bringing the blood to the 
surface to be acted on by atmospheric air. 
I have endeavoured to ascertain if there is any direct com- 
munication by spiracula through the integuments. The 
results I have obtained have been negative. I have intro- 
duced air through a small incision, by means of a forcing 
syringe, under the loose skin, also into the cavity of the 
abdomen, and into the lungs by the superior glottis. The 
air has been very much compressed under water, yet it has 
been completely confined, not the smallest bubble having 
been forced through the skin, or the lungs. 
When dried, the skin of the toad exhibits two kinds of 
pores ; one kind, few in number, confined to the two tube- 
rosities over the shoulders, sufficiently large to admit a hog’s 
bristle ; the other kind, very numerous, scattered over the 
whole surface, and very minute. They are both of them 
best seen by holding the skin between the eye and a strong 
light ; the smallest appears as luminous points of a yellow 
hue ; the largest as indistinct circles. Both are covered 
externally with transparent cuticle, and internally by a deli- 
cate surface of cellular tissue ; some of the largest are also 
covered with rete mucosum ; the smallest appears to be 
destitute of this membrane. 
