262 CUTANEOUS FOLLICLES OF THE TOAD. 



portion of carbon from the blood, and thus be auxiliary to the 

 function of the lungs. In support of this idea the same 

 author observes tliat each of the pulmonary arteries of the 

 Toad divides into two branches, one of which goes to the lungs, 

 the other to the cutis, ramifying most abundantly where the 

 largest follicles are situated, and where there is a large venous 

 plexus, seeming to indicate that the subcutaneous distribution 

 of the second branch of the pulmonary artery may further aid 

 the office of the lungs by bringing the blood to the surface to 

 be acted upon by the air. However, it seems to me that if 

 these follicles aid at all the lungs, it can only be by elimi- 

 nating carbon set free in other organs of the body, and then 

 conveyed into the blood, from whence they afterwards ex- 

 crete it ; as the deep position of their capillaries, and the 

 secretion with which tliey are always more or less thickly 

 covered, will make them inaccessible to the atmospheric 

 air, and therefore, in this respect, render them altogether 

 different from the cutaneous capillaries which are placed su- 

 perficial to the earthy layer of the dermis, and in which the 

 blood is perhaps acted upon, as above intimated. But I 

 cannot help thinking otherwise than that these follicles have 

 something to do with the absorption, and more especially 

 with the retention, of the fluid which, in this class of reptiles, 

 is taken into the system by the skin. In the Frogs there is a 

 superficial plexus of capillaries the same as in the Toads, by 

 which the absorption of the fluid in contact with the surface, 

 can take place equally in either case ; but in the former ani- 

 mal there are no cutaneous organs which could in any manner 

 aid in the retention of that fluid, so that this reptile requires 

 more frequently than the toad a fresh application of moisture 

 to its surface ; and besides, if the Frog be exposed to the 

 absorbent power of dry mould, as the Toad frequently is, the 

 greater part of the fluid contained in its vessels will imme- 

 diately pass off through the skin into the dry earth in conse- 

 quence of its greater capillary attraction, and the animal will 

 very soon die from a kind of inanition. This fact I have 

 verified by placing fine dry sand in contact with the skin of 

 Frogs, which so rapidly absorbs their moisture that they die 

 in a few minutes. Tiie contents, also, of the follicles of the 

 toad, mixing with the dust and other extraneous substances 

 constantly in contact with its skin, especially as this secretion 

 is of a very glutinous nature, and has a tendency to coagulate 

 when wetted, may possibly form a coating on its external sur- 

 face, and thus tend to diminish evaporation ; and in this way 

 it may assist in retaining the fluids absorbed into the body, 

 and in preventing its desiccation, and thus furnish another 



