Full resolution (JPEG) - On this page / på denna sida - XVII. Metabolism - I. General Discussion and Methods used in the Study of Matter and Force Metabolism
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
NITROGEN ELIMINATION. NITROGEN DEFICIT. 881
fluids. It may not vary in different individuals only, but also in the same
individual after more or less active secretion and absorption. In the
attempts made to determine this part of the nitrogen of the excrement
it has been found that in man, on non-nitrogenous or nearly nitrogen-
free food, it amounts in round numbers to somewhat less than 1 gram
per twenty-four hours (Rieder, Rubner). Even with such food the
.absolute quantity of nitrogen eliminated by the feces increases with
the quantity of food because of the accelerated digestion (Tsuboi 1
),
and is greater than in starvation. Muller 2
found in his observations
on the faster C’etti that only 0.2 gram nitrogen was derived from the
intestinal canal.
The quantity of nitrogen which leaves the body under normal circum-
stances by means of the hair and nails, with the scaling off of the skin,
and with the perspiration cannot be accurately determined. It is
nevertheless so small that it may be ignored. Only in profuse sweating
need the elimination by this channel be taken into consideration.
The view was formerly held that in man and carnivora an elimination
of gaseous nitrogen took place through the skin and lungs, and because of
this, on comparing the nitrogen of the food with that of the urine and
feces, a nitrogen deficit occurred in the visible elimination.
This question has been the subject of much discussion and of numerous
investigations, the most recent by Krogh and Oppenheimer.3
These
researches have shown that the above assumption is unfounded, and
moreover several authorities, especially Pettenkofer and Voit, and
Gruber,4
have shown by experiments on man and animals that with
the proper quantity and quality of food the body can be brought into
nitrogenous equilibrium, in which the quantity of nitrogen voided with
the urine and feces is equal or nearly equal to the quantity contained in
the food. Undoubtedly we must admit, with Voit, that a deficit of nitro-
gen does not exist, or it is so insignificant that in experiments upon
metabolism it need not be considered. Ordinarily, in investigations on
the catabolism of proteins in the body, it is only necessary to consider the
nitrogen of the urine and feces, but it must be remarked that the nitrogen
of the urine is a measure of the extent of the catabolism of the proteins
1
Rieder, Zeitschr. f. Biologie, 20; Rubner, ibid., 15; Tsuboi, ibid., 35.
2
Berlin, klin. Wochenschr., 1887.
3
See Regnault and Reiset, Annal. d. chem. et phys. (3), 26, and Annal. d. Chem.
U. Pharm., 73; Seegen and Nowak, Wien. Sitzungsber., 71, and Pfliiger’s Arch., 25;
Pettenkofer and Voit, Zeitschr. f. Biologie, 16; Leo, Pfliiger’s Arch., 26; Krogh,
Skand. Arch. f. Physiol., 18, and Wien. Sitz. Ber., 115, III; Oppenheimer, Bioch.
Zeitschr., 4.
4
Pettenkofer and Voit, in Hernnan’s Handbuch, 6, Thl. 1; Gruber, Zeitschr. f.
Biologie, 16 and 19.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
