162 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[August 27, 1870. 
individuals should he proportionate to the respective 
mass of their muscles, while the duration of the work 
should he proportionate to the supply of material 
suitable for restoration of the transformed parts of 
the muscular mass. 
The comprehensive and carefully conducted inves¬ 
tigations of Playfair in reference to the requirements 
of various classes for albuminates in their daily food, 
appear to leave no doubt as to the correctness of this 
view. He demonstrated that everywhere and under 
all conditions, the labourer required, for the mainte¬ 
nance of working power and health, a larger amount 
of albuminates than was needed by an individual that 
no work. This is the case in prisons, in peniten¬ 
tiaries, and with soldiers both in war and in peace. 
Moreover, the results of Playfair’s investigations 
have not encountered any earnest opposition resulting 
from observations of equal value. Isolated observa¬ 
tions have been urged against his conclusions ; but 
I consider that these should be regarded with as much 
caution as the opinion popularly held in Bavaria, 
that beer is a good article of nutrition and that 
hard-working men owe their strength chiefly to the 
consumption of beer. Exact observation of the diet 
of the brewery labourers in Munich, who consume 
the largest amount of beer, shows, on the contrary, 
that these people are also the largest meat-eaters.* 
The question as to the source of muscular power 
has been rendered confused by an inference that has 
proved to be erroneous, and for which I am myself 
accountable. If the muscular substance in under¬ 
going metamorphosis be the source of muscular 
power and, if the ultimate nitrogenous product 
formed hi this metamorphosis with the aid of oxygen 
be urea, then it would follow (it was erroneously in¬ 
ferred) that the work done might be deduced from 
the quantity of urea. It was assumed that the 
metamorphosis would be proportionate to the work 
clone and that the urea secreted would be also pro¬ 
portionate to it. 
The first facts ascertained in opposition to this view 
that urea was a measure of muscular work, were es¬ 
tablished by Dr. Bischoff in his investigation on urea 
as a measure of metamorphosis. Then followed the 
still more comprehensive investigation, undertaken 
by Bischoff and Yoit in Munich, which may be re¬ 
garded as a continuation of the experiments made 
at Giessen. It is probably unnecessary to mention 
here that I have always taken the liveliest interest 
in these investigations; indeed, the method devised 
by me for estimating urea owes its origin to them. 
In these experiments a clog was feci with known 
quantities of meat and fat, with meat alone, with 
meat, carbohydrates and gelatin. At the same time 
the daily quantity of area secreted was determined. 
The quantity of nitrogen in the meat and the 
urine being known, it might be assumed in calculation 
that when the nitrogen in the urine was found to 
equal that in the meat consumed, the whole of the 
meat had been metamorphosed; if the quantity of 
urea was less, a portion of the meat consumed must 
have remained in the body or, in other words, must 
. * In the brewery of Sedlmayer, at Munich, 95 workmen, 
six women, and nine children, in all 112 persons, consumed 
11,189 kilog. bread, 17,870 kilog. meat, and 159,120 litres of 
beer from the 1st October to the 30th April. Reckoning the 
6 women and 9 children as equal to 9 men, the daily quantity 
of meat consumed per head would be 810 grm. The work of 
the brewery labourers is the most severe of any, and only very 
strong men are fit for it. 
have been assimilated, while if the quantity of nitrogen 
was greater, the excess must have been furnished by 
parts of the body. 
The following are among the most important 
results of these experiments:— 
With a certain proportion of meat and fat, the 
animal experimented upon could be maintained at a 
constant weight. In this case all the nitrogen ap¬ 
peared as urea in the urine, and since there was no in¬ 
crease of weight, the fat must have been consumed 
in respiration. 
It then became apparent that by increasing the 
supply of meat without increasing that of fat, the 
quantity of urea secreted became greater in the same 
proportion as the meat supply had been increased, 
while at the same tune the weight of the animal in¬ 
creased. 
In opposition to the opinion, then prevailing, that 
fat lessened the metamorphosis in the body—in¬ 
asmuch as it appeared to be far more susceptible 
of oxidation than flesh—it followed from this ex¬ 
periment, on the contrary, that an excess of meat 
took the place of fat in the process of respiration. 
While, in the former case, the fat was entirely used 
up, it appeared that with more meat a part of this 
fat remained unaltered in the body. 
This fact acquires high significance in a particular 
direction, inasmuch as it proves that there is in the 
animal body an arrangement by which increase of 
the blood or of constituents of blood beyond a cer¬ 
tain limit is prevented. When albuminates are sup¬ 
plied in quantities greater than the body is in need 
of, they are removed in the most speedy way. 
The particular causes that destroy this excess 
cannot, under normal conditions of nutrition, exer¬ 
cise any action upon the constituents of the blood; 
for, otherwise, in the case of deficient supply of food, 
or during abstinence, those constituents would be as 
much subject to the destructive influence of such 
causes, as if the excess of those constituents in the 
food had been acted upon. 
It was further shown by Bischoff and Yoit that 
the animal experimented upon could be sustained 
upon meat entirely destitute of fat and maintained 
at its full weight with very slight variations. In this 
case the secreted urea corresponded in quantity to 
the nitrogen of the meat consumed. 
The constancy of the animal’s weight indicated 
that fat may be entirely replaced by meat in the 
process of respiration ; one part of the meat had un¬ 
doubtedly served for generating heat, while another 
part served for the restoration of metamorphosed parts 
of the body. 
But in both cases the nitrogenous product of the 
meat was the same, viz. urea. 
However, if urea were a product not only of meta¬ 
morphosis, but simultaneously also of respiration, 
then the quantity of urea secreted could not afford any 
indication as to the extent of the metamorphosis. 
If, moreover, the muscular work were determined by 
the metamorphosis, the amount of work could not be 
measured by the urea secreted. The view previously 
held could only be maintained if it could be shown 
that the work done by the animal was augmented in 
proportion as the supply of meat was increased. 
In this case it must have been assumed that the 
meat was converted into muscle, that this muscle 
was metamorphosed, and that the products of this 
metamorphosis had served as material for generating 
heat. 
