LACK OF IKON. 903 



phosphorus. Also the investigations of v. WENDT and HOLSTI 1 show 

 that a synthesis of organic phosphorized substances from phosphates is 

 very probable. The feeding experiments of OSBORNE and collabora- 

 tors, which we will soon discuss, and wilich extend over a long period 

 where the animals were fed with proteins, fat, carbohydrates and min- 

 eral substances free from phosphorus, give especially strong proof of 

 the ability of the animal to construct phosphatides and nucleins from only 

 inorganic phosphorus. 



Lack of Iron. As iron is an integral constituent of haemoglobin, 

 absolutely necessary for the supply of oxygen, it is an indispensable 

 constituent of food. Iron is a never-failing constituent of the nucleins 

 and nucleoproteins, and herein lies another reason for the necessity 

 of the introduction of iron. Iron is also of great importance in the 

 action of certain enzymes, the oxidases. In iron starvation, iron is 

 continually eliminated, even though in diminished amounts; and with 

 an insufficient supply of iron with the food the formation of haemoglobin 

 decreases. The formation of haemoglobin is not only enhanced by the 

 supply of organic iron, but also, according to the general view, by inor- 

 ganic iron preparations. The various divergent reports of this question 

 have already been given in a previous chapter (on the blood). 



In the absence of protein bodies in the food the organism must nourish 

 itself by its own protein substances, and with such nutrition it must sooner 

 or later succumb. By the exclusive administration of fat and carbohy- 

 drates the consumption of proteins in these cases is very considerably 

 reduced. For a long time we believed in the view suggested by C. and E. 

 VOIT 2 that with a nitrogen- free diet the protein metabolism could never 

 be reduced to as small a value as in starvation, but now, due to the investi- 

 gations of HlRSCHFELD, KUMAGAWA, KLEMPERER, SlV^N, LiANDERGREN" 



and recently those of THOMAS, S we learn that the protein metabolism 

 with such a diet can be smaller than in complete starvation. With exclusive 

 feeding of sugar, according to THOMAS, the nitrogen elimination can be 

 reduced in a few days to the wear and tear quota, and he has observed 

 an elimination of only 30 milligrams nitrogen per day and per kilo of 

 body weight. 



The absence of fats and carbohydrates in the food affects carnivora and 

 herbivora somewhat differently. It is not known whether carnivora 



1 v. Wendt, Skand. Arch. f. Physiol., 17; Holsti; ibid., 23. See also Gregersen, 

 Zeitschr. f. physiol. Chem., 71. 



2 Zeitschr. f. Biologic, 32. 



'Hirschfeld, Virchow's Arch., 114; Kumagawa, ibid., 116; Klemperer, Zeitschr. 

 f. klin. Med., 16; Sive"n, Skand. Arch. f. Physiol., 10 and 11; Landergren, 1. c., 11; 

 footnote 1, page 894, also Maly's Jahresber., 32; Karl Thomas, Arch. f. (Anat. u.) 

 Physiol., 1909 and 1910, Suppl. Bd. 



