80 SOURCES OF ANIMAL HEAT AND MOTION. 
the cutis may be truly said to rest upon a bed of fatty tissue 
(paniculus acliposus) ; the upper surface of the areolar tissue 
of the cutis is thrown into papillae, covered with elongated 
perpendicular cells, forming the deeper layer of the rete 
Malpighii ; the cells above these are roundish, and those 
nearest the cuticle becoming longer, horizontally flattened 
from mutual pressure. The cells of the cuticle are co¬ 
lourless, flattened, often wrinkled or folded. All the cells 
of the rete Malpighii agree in essential points in their struc¬ 
ture, and are nucleated vesicles distended with fluid. The 
contents are finely granulated, with more or less clearly 
defined granules, which invariably diminish in number 
in the more external cells; they also yield fat when boiled 
in concentrated solution of caustic potassa (Kolliker) ; 
The skin is abundantly supplied with fatty matters, 
whilst the large quantity of blood in the endless folds 
of the capillaries presents a constant source of oxygen; here 
then every condition is fulfilled requisite for the pro¬ 
duction of heat. The rapid growth of the epidermis, the 
hair, and the nails, must not be forgotten. A new nail is 
formed on the thumb in twenty weeks. Hairs of the beard, 
shaved every twenty-four hours, grow at the rate of 
51 inches per annum (Berthold). The epidermis, hair, and 
nails, all consist of epithelial scales, and since these scales are 
but membranes, or the mere w r alls of the Malpighian cells , 
I beg to ask the physiologist what becomes of the cells' 
contents? After long and careful examination of this 
subject, it is my humble opinion that the cells of the 
rete Malpighii are the seat of an extraordinary rapid meta¬ 
morphosis which generate heat—in fact, they are the main 
source of animal heat. 
The labours of the eminent physiologists, Matteucci and 
Brown-Sequard, have recently established a new fact in phy¬ 
siology, viz., the existence of i( muscular respiration." May 
we not have a ££ cutaneous respiration 
In conclusion, as the term cutaneous respiration may lead 
to error, I wish it distinctly understood that all oxygen 
employed for this and every other vital phenomenon in the 
animal organism can only enter it through the lungs. Again, 
that the vital force of the untransformed cells resists the action 
of oxygen until their normal temperature is disturbed or lost; 
the cooling of the skin by the atmosphere enables oxygen to 
effect the metamorphosis of the cells, if the rete Malpighii 
generate heat, and thus maintain the natural temperature of 
the skin.— Spirit of the Times. 
