308 HENRY A. MATTILL AND HELEN I. MATTILL 



the composition of the blood is fixed, but rather that it varies within nar- 

 rower limits than those for the composition of the organs. 



Of the less abundant mineral elements Gautier has called attention to 

 'the wide distribution of F(d) and As(a) in the organism. F bears rather 

 a striking relation to P ; in the soft tissues and glands P : F is about 450, in 

 the supporting tissue, bone and cartilage it is 125 and in the epidermis, 

 hair and nails it is approximately 4. Injection of NaF into rabbits has 

 been found to have an undesirable effect on Ca metabolism and F in foods 

 is to be avoided (Schwyzer). Arsenic, Gautier found in the thymus and 

 thyroid, in menstrual blood, in hair and skin. Bertrand confirmed these 

 findings, which have been denied by others, possibly because organic As 

 compounds would escape ordinary analytical methods. Van den Eeckhout 

 found that ingestion of As promoted growth and well-being in animals. 

 Bang(/) found that As in the urine varies greatly, depending on the 

 amount in the foodstuffs, and may reach 0.5 mg. daily. Fish is especially 

 high in As and on a fish diet he found 0.78 mg. As daily, while on a vege- 

 tarian diet the urine was As-free. 



Silica is normally present in the urine and feces in amounts fluctuating 

 with the intake (Schulz(a)). It is widely distributed in the body and 

 comprises 40 per cent of the ash of hair and seems to be an essential con- 

 stituent of the pancreas. Kahle calls attention to the loss of SiO 2 by the 

 pancreas and its increase in the lymph glands of tubercular cattle, and to 

 its increase in the pancreas in carcinoma. He found that the administra- 

 tion of the organic preparation of silica made by Weyland had a beneficial 

 influence on the formation of connective tissue in the affected organs of 

 tubercular guinea pigs. Schulz(c) considers that Kahle is not justified 

 in his generalizations since there is a wide variation in the SiO 2 content of 

 glands of tuberculous and carcinomatous patients. He found 0.0084 per 

 cent SiO 2 in the normal dry thyroid and a larger amount in pathological 

 thyroids(&). Gassmann(6) has identified selenium in teeth and bones. 

 Mn (Reiman and Minot; Bertrand and Medigreceanu) is widely dis- 

 tributed in the human organism and is highest in the liver, averaging 

 0.17 mg. per 100 g. moist tissue. The blood contains 0.004-0.024 mg. Mn 

 per 100 g., its function is probably catalytic. Small amounts of Cu and 

 Zn are widely distributed in the body and always present in the urine and 

 feces, their sources being undoubtedly the ingested foods (Van Itallic and 

 Van Eck; Rost and Weitzer). 



Older conceptions of the relative unimportance of salts for nutrition 

 and the easy assumption that a normal mixed diet always supplied what- 

 ever need there might be for inorganic elements have recently given way to 

 a recognition of the very definite needs of the body with respect to min- 

 eral constituents. Forster first established the fact that salt-poor diets 

 led to faulty nutrition. What little work has been done on the ingestion of 

 a salt-free diet leads to the conclusion that salts in the food are not pri- 



