THE METABOLISM OF THE BODY. 445 
purposes are probably served, as will appear from later consid- 
erations. 
Pathological.—Corpulence, or excessive fat formation, leading 
to the hampering of respiration, the action of the muscles, and, 
to a certain extent, many other functions of the body, does not 
arise usually till after middle life, when the organism has 
seen its best days. It seems to indicate, if we judge by the 
frequency of fatty degeneration after disease, that the proto- 
plasm ‘stops short of its best metabolism, and becomes de- 
graded to a lower rank; for certainly adipose tissue does not 
occupy a high place in the histological scale. Many persons 
given to excessive fat formation are fond of saccharine and 
amylaceous ‘foods; but the fact that, under the strictest diet, 
the abnormality can be but moderately controlled, shows that 
the main point is the existence of the habit of certain cells 
naturally to form fat, which, in disease, becomes exaggerated, 
or is taken up by others that normally have little share in 
such work. Such pathological facts throw a good deal of light 
upon the general nature of fat excretion, as it would be better 
to term it, perhaps, and seem to warrant the view that we have 
presented of the metabolic processes. 
Although the nerves governing the secretion of milk have 
not been traced, there can be no doubt that the nervous system 
controls this gland also. The influence of the emotions on both 
the quantity and quality of the milk in the human subject and 
‘in lower animals is well known. There seems to be no doubt 
that milk of an injurious if not absolutely poisonous character 
may be formed under the influence of depressing or unusually 
exciting emotions, as grief, rage, etc. We know less about the 
influence of the nervous system in fat formation elsewhere, 
though it is well enough established that persons grow thin 
under worry as well as excessive mental and physical exertion. 
In the latter case, it is not improbable that the overworked 
muscles may draw, in some way, on the stored fat. At the 
same time, fat formation may be interfered with, and be an ex- 
pression of the unnatural conditions generally that have been 
established. Such cases are too complex to permit of being 
completely unraveled. 
Comparative—While breeders recognize certain foods as 
tending to fat formation and others to milk production, it is 
interesting to note that their experience shows that race and 
individuality, even on the male side, tell. The same conditions 
being in all respects observed, one breed of cows gives more 
