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902 METABOLISM.
of calcium phosphate by the skeleton. It is impossible to give
positive figures for the need of phosphates or phosphoric acid, whose
value is recognized not only in the construction of the bones, but also’
in the functions of the muscles, the nervous system, the glands, the
organs of generation, etc. The extent of this need is most difficult to
determine, as the body shows a strong tendency, when increased amounts
of phosphorus are introduced, to retain more than is necessary. The
need of phosphates, which, according to Ehrstrom,1
corresponds in adults
to a minimum of 1 to 2 grams phosphorus, is relatively smaller in adults
than in young, developing animals, and in these latter the question of
the result of an insufficient supply of earthy phosphates and alkaline
earths upon the bone tissue is of special interest. For details we refer
to Chapter IX and to the cited work of Albu-Neuberg.
Another important question is, How far do the phosphates take part
in the construction of the phosphorized constituents of the body or to
what extent are they necessary? The experiments of Rohmann and his
pupils 2
with phosphorized (casein, vitellin) and non-phosphorized pro-
teins (edestin) and phosphates show that with the introduction of casein
and vitellin a deposition of nitrogen and phosphorus takes place, while
with non-phosphorized protein and phosphates this does not seem to
occur. The body apparently does not have the power of building up
the phosphorized cell constituents necessary for cell life from non-phos-
phorized proteins and phosphates. On the contrary, according to the
observations of several investigators, the lecithins seem to possess this
power. As known from the investigations of Meischer, the develop-
ment of the generative organs of the salmon, which are very rich in nuclein
substances and phosphatides, from the muscles which are relatively poor
in organic-combined phosphorus, seem to indicate a synthesis of phos-
phorized organic substance from the phosphates. The investigations
of Hart, McCollum and Fuller,3
who found that pigs with food
poor in phosphorus develop just as well with inorganic phosphates as,
with organic phosphorus compounds, also indicate such a formation.
The recent investigations of McCollum 4
on rats show that these animals
can take up the entire need of phosphorus for the skeleton as well as for
the reformation of nucleins and phosphatides in the form of inorganic
1
Skand. Arch. f. Physiol., 14.
2
The literature on feeding experiments with phosphorized and non-phosphorized
food can be found in McCollum, Amer. Journ. of Physiol., 25.
1
Hart, McCollum and Fuller, Amer. Journ., of Physiol., 23. See also Lipschiitz,
Pfliiger’s Arch., 143. The literature on the phosphorus metabolism can also be
found in Albu and Neuberg, Physiologie und Pathologie des Mineralstoffwechsel,.
Berlin, 1906.
4
Amer. Journ. of Physiol., 25.
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