Dr. Beale, on Nutrition. 
79 
of a concretion, or a crystal, which increases by the superpo- 
sition of layer upon layer ! 
I propose now to refer briefly to the process of nutrition 
as it occurs in man and the higher animals. It has been said 
that the life of the body is the blood, and it has been surmised 
that from' this fluid the tissues derive not only the elements 
of their nutrition, but their life or the properties which we 
call by that name. It is, however, more probable that the 
blood contains only nutrient pabulum adapted for the nutri- 
tion of the tissues, which, like all nutrient matter, is lifeless , 
not living. The actual nutrition, the conversion of the pabulum 
that was in the blood into tissue, is due to actions which 
occur outside the vessels containing the passive nutrient 
blood. As little supported by facts as the opinion above 
alluded to is the doctrine that arterial blood takes special 
part in the nutrition of tissues, although a student reading 
any of our text books would be led to believe that the highly 
nutritive properties of arterial blood had been proved beyond 
all question, and that every tissue to be nourished must have 
its nutritive artery. The very active nutrition going on in 
the lower animals and plants under conditions not favorable 
to free oxidation, and the fact that in man and the higher 
animals during the early periods of life when nutritive acti- 
vity is most remarkable, the blood is not so highly oxygenated 
as at a later time when the nutritive operations are compara- 
tively slowly carried on, seem to show the fallacy of such a 
view. 
Every one knows that food nourishes the body, and that 
the tissues are nourished by the blood, and it is generally 
believed that a high state of nutrition depends upon a liberal 
diet. At the same time, however, we know that the degree 
of nutrition exhibited by the body is not dependent merely 
upon the quantity or quality of the food introduced into the 
stomach, absorbed and converted into blood, but ujion many 
other circumstances. In one individual much of the food 
may be excreted in an altered form soon after it has been in- 
troduced into the system, while in another a large proportion 
may be converted into tissue. This difference is determined 
not by the pabulum, but by the living material which is 
destined to take this up, and which is concerned in the for- 
mation of tissue. Some men and some animals soon become 
fat upon a diet which to others would be extremely low ; 
while certain individuals cannot be made fat, although sup- 
plied with abundance of the choicest food. We must also 
bear in mind that every tissue does not share in the increased 
nutrition, and although we often talk familiarly of the in- 
