( 148 ) 
On the Organs of Cutaneous Respiration ; principally on 
those of the Rana temporaria. By George Harley^ 
M.D.^ F.C.S., Teacher of Practical Physiology and His- 
tology in University College^ London. 
(Read March 4th, 1857.) 
The theory of cutaneous respiration is now regarded as an 
established doctrine. Among some of the lower animals the 
interchange of gases by means of the skin is performed in 
so perfect a manner as to be in itself capable of supporting 
life. Bischoffj and other observers_, found that even certain 
Batrachia live during several hours after the extirpation of 
their lungs; the aeration of the blood being accomplished by 
the cutaneous surface alone. The peculiar function which 
the skin possesses of absorbing oxygen_, and exhaling car- 
bonic acid_, is not confined entirely to animals low in the 
scale of development ; it has been traced throughout the 
whole animal kingdom. Experiments performed on the human 
subject by Scharling^ Valentin, Brunner, Andral, and a great 
many others, have clearly demonstrated that even the cuta- 
neous surface of man has an important share in the respira- 
tory process. As far as I am aware, however, no one has 
attempted to describe the construction of the apparatus by 
which the interchange of gases takes place. The following 
observations may perhaps therefore prove interesting, from 
the simple fact of their novelty. 
Several months ago, while studying the physiology of cuta- 
neous respiration, I was desirous to ascertain if the skin 
possessed special organs for the aeration of the blood. With 
the human skin, however, I found it impossible to arrive at 
any satisfactory conclusion, and therefore directed my atten- 
tion to the examination of the skins of animals possessing a 
more highly developed cutaneous respiration. The frog 
being easily obtainable, and at the same time well suited for 
the investigation of this subject, was first examined. 
On placing under the microscope a small portion of the 
epidermis from the back of the animal, the immense number 
of openings in it immediately arrested my attention. And 
on examining these openings more narrowly, I found, that 
what I had supposed to be the mouths of the organs usually 
designated cutaneous glands, possessed a remarkable resem- 
blance to the stomates of plants."^ Each opening appeared 
* The observations related in the following pages were made in 1855, 
and in the latter part of that year I showed the peculiar openings in the 
skin of the frog to Professors Sliarpey and Ellis, and several other gentle- 
