In a study of the growth of tumors in mice Van Alstyne and Beebe77 found that 24 out of 26 animals on a diet of casein, lard and lactose grew a tumor with fatal results, while on a diet of casein and lard only two were killed by the tumor. Sweet, Corson-White and Saxon 78 argued that this result was due to the growth-stimulating effect of the accessory substance introduced with the lactose.78a From their investigations they concluded that tumor cells are subject to the same laws of growth as normal somatic cells, the only difference being that the tumor cell possesses stronger avidity for the unknown substance in the diet which is essential for cell growth, and will therefore persist in developing even though the individual is losing weight.79

While data is constantly accumulating regarding the indispensa-bility of the vitamins and the disastrous effects due to scarcity of these factors, hypotheses as to their precise physiological function are few and vague. McCarrison80 believes that the whole morbid process indicative of vitamin deficiency is the result of nuclear starvation of all tissue cells, since even the adrenals, which alone of all the organs of the body undergo enlargement, show on sectioning, changes in some of their cells indicative of nuclear starvation. This, however, merely changes the form of the question and leaves us asking what derangement of functions and processes causes this nuclear starvation. Portier's theory80a that the vitamins impregnate nuclear substance bringing about " nuclear fecundation" and thus furnishing the cells with an impetus without which they cannot live, is equally vague.

Arguments based on the distribution of the vitamins in the tissues are unconvincing, partly because of the contradictory data given by different observers, and partly because of the variety of interpretations possible for the accepted results.

McCollum has attempted to correlate high vitamin content with actively functioning cells, with the inference that the presence of vitamins in such cells is indispensable for their development.

Steenbock and Gross81 point out that this relation does not by any means invariably hold in the plant kingdom, as is shown by the great variation in the A content of similar organs, such as tubers and roots. Drummond 82 has shown that actively growing animal tissues such as embryos and tumors do not contain appreciable amounts of B. Swoboda, using a modification of the Williams' yeast test,83 could detect little vitamin in tissues high in nuclear material such as thymus and lymph gland, while, on the other hand, yeast with its high content of nuclear material is one of the richest sources of vitamin.

77 Van Alstyne and Beebe, J. Med. Res. 24, 217, 1913-14. 8ee p. 909.

78 Sweet, Corson-White and Saxon, J. Biol. Chem. 21, 314, 1915.

79 See also Corson-White, Penn. Med. J. 22, 348, 1919.

78a Hawk, Smith and Bergheim report that strained honey does not appear to contain appreciable amounts of vitamins A, B and C. Honeycomb contains moderate amounts of A. (Am. J. Physiol. 55, 339, 1921).

80 McCarrison, Ind J. Med. Res. 6, 275, 550, 1919.

80a Portier, Bull. soc. sci. hyg. 8, 521, 603, 1920.

81 Steenbock and Gross, J. Biol. Chem. 40, 503, 1919.

Steenbock and Gross 84 consider that the vitamin content of liver tissue, instead of being due to or associated with its activity as a glandular organ, might with equal propriety be looked upon from the standpoint of its well known functions as a storage organ, or might possibly be attributed to the absorption of substances not indispen-sible to the organ but absorbed due to an inefficiency of the mechanism which excludes the entrance of substances in amounts greater than the needs as these substances are brought to it in the portal circulation. Similarly the high vitamin content of the kidney may be said to be due to the temporary retention of the vitamin. Voegtlin and Towles 85 found from observations made on the vitamin content of the spinal cord that nerve fibres contain the anti-neuritic substance, mainly in combined form, which is liberated after autolysis of the tissue, and judged from this that the antineuritic substance under normal conditions formed an essential part of the nerve fibre, and that its presence in the nerve tissue in sufficient amounts is essential for proper functioning of this organ.

The long list of compounds, unrelated chemically, such as betaine, allantoin, certain pyrimidines,86 nicotinic acid,87 adenine,88 crhydroxy-pyridine,89 thyroxin (trihydrotriiodo-oxyindol-propionic acid), pilocarpine, teth-elin,90 a-ketog - propylindol, and n-methyl-jg-ethylindolinone,91 which have been found to exert a curative effect upon avian polyneuritis would seem to indicate, however, that the function of the antineuritic vitamin may be merely to provide nerve stimulant, an effect which might equally well be produced indirectly.

Uhlmann92 concluded that the antineuritic vitamin acts on the sympathetic nerve endings and thus exerts a controlling influence on the tones of the muscles in the organism. He was led to this conclusion by the observation that vitamin extracts act upon animal tissues very much as do pilocarpine and choline. The intestinal muscles are caused to contract, the action of the heart is depressed, the blood pressure is lowered, and the blood vessels dilated exactly as occurs when the respective tissues are treated with pilocarpine.98 Moreover, the action of the vitamin, like that of pilocarpine or choline, is antagonised by atropine.

82 Drummond, Bioch. J. 12, 25, 1918.

83 Swoboda, J. Biol. Chem. 44, 639, 1920.

84 Steenbock and Gross, J. Biol. Chem. 40, 503, 1919.

85 Voegtlin and Towles, J. Exp. Pharm. 5, 67, 1913.

86 Punk, J. Physiol. 45, 489, 1912-13. 87 punk, Ib., 46, 177,1913.

88 Williams and Seidell, J. Biol. Chem. 26, 431, 1916.

89 Williams, lb 29, 504, 1917.

90 Dutcher, J. Biol. Chem. 39, 63, 1919.

91 Dutcher, Holm, and Bierman, Sci. 52, 589, 1920.

92 Uhlmann, Zeitsch. Biol. 68, 457, 1918.