In this connection note should be made of Funk's experiment,22 in which the extract of tissues of birds which had been killed in the last stages of polyneuritis were found to be as efficacious for the cure of this disease as tissue-extracts from healthy birds.

Preliminary experiments in an investigation aimed to test the comparative amount of antiscorbutic substance in eggs and in newly-hatched chickens appear to give some additional weight to the probability of a synthesis of antiscorbutic substance by certain animal tissues, or a utilization of forms other than those available to the guinea pig.

The specific diseases known as the "deficiency diseases" which result from prolonged restriction in or complete deprivation from vitamins are discussed in detail elsewhere. Here it is sufficient to summarize the symptoms which have been observed in animals and human beings as the result of limitation in the vitamin content of the diet.

The most obvious symptoms of deficiency of A shown by young animals are lack of growth, diminished appetite, decline and wasting of the tissues to emaciation, sometimes accompanied by diarrhoea, weakness, lack of resistance to infection and disease, and ultimate death.23 An inflamed condition of the eyes is very commonly reported (for discussion see p. 234 and ff.24).

22 Funk, Zeit. f. Physiol. Chem. 89, 373, 1914. 23 Osborne and Mendel, J. Biol. Chem. 16, 431; 17, 401,1914. 24 Drummond, Lanoet, 1918, ii, 482; Bioch. J. 13, 96, 1919. Osborne and Mendel, 20, 379, 1915. See also Steenbock, Soi. Monthly, 7, 179, 1918.

Mellanby,25 while not denying the necessity of A for growth, believed that the amount of growth of a puppy has no relation to the amount of A in the diet, although a small minimal amount may be necessary. He notes the possibility that puppies have a sufficient store of A in their own tissues to allow of growth for several months, independently of what may be in the diet. " Large and rapidly growing puppies require more of the antirachitic factor to prevent rickets If, therefore, this factor is identical with A, the presumption is that the function of A in the diet of puppies is not so much to ensure growth as to promote correct growth; and the greater the amount of growth in any period, the greater is the amount of fat-eoluble A necessary to keep it along normal lines. If this view is correct it can hardly be claimed that A is in any different category from the point of view of growth than is the antiscorbutic factor, for even in the absence of this latter the rate of growth diminishes and there is often rapid loss of weight."26*

Davis 26 has carried on a series of long-time experiments in which several generations of rats were kept on a diet deficient in A. The ration used consisted of crushed oats, polished rice and skimmed milk ad libitum and a limited amount of cooked potato and egg white. On this ration the half-grown males grew at 80 to 90 per cent of the normal rate for three months. After a period of maintenance they became emaciated and died. None lived longer than eight months.

Most of the females reared one litter and a few reared two on the ration. All but three of the litters were born in the first two months. A second litter of four young was born when the mother had been 148 days on the ration. A female from this lot reared a litter of two young. She was 135 days old at parturition, which made 283 days since the beginning of the experiment. When the young were 25 days old they were discontinued. This made 306 consecutive days for the three generations. Distended abdomens were conspicuous in all of the young born on the ration. In some cases this disappeared after four to five months. Xerophthalmia which Osborne and Mendel and also McCollum and Simmonds have reported in the absence of the fat-eoluble vitamin appeared at four to five months in the rats born on the ration. In less than 200 days all of the animals had either died or were chloroformed in an emaciated condition. In the litter of 11 young of the second generation born on the ration, in addition to the distended abdomen, and xerophthalmia, small haemor-rhagic spots appeared on the tails, and when they were about 30 days old the end of the tails dropped off.

The eyes were pale and a blood count showed 4,000,000 to 5,000,000 red blood cells in contrast to a normal count of 8,000,000. A post-mortem examination of the rats put on the ration as well as those born on the ration showed the stomach and intestines filled with gas, the intestines dull and brown, and no intraperitoneal fat visible. Autopsy of the second generation born on the ration revealed very marked anaemia. The lungs were white and the liver and kidneys were sand color. The bones were very fragile. There was no apparent beading of the ribs.

25 Mellanby, Lancet, 1919, i. 407.

26 Attention is called by Potter (Intern. J. Pub. Health x, 86, 1920; Expt. Sta. Record 44, 62) to the apparent diversity of opinions and experimental facts in recent contributions to the literature of vitamins and to the possibility of harmonising some of these diversities.

26 Private communication, 1920. See also Davis and Outhouse, Am. J. Dis. Child, 21, 307, 1921.

A histological examination was made on rats from most of the litters. The organs examined were heart, spleen, liver, lung, pancreas, kidney, and testes. The tissues were removed immediately at autopsy and fixed in Zenker's fluid, imbedded in paraffin, cleared in xylol, and stained with haemotoxylin and eosin, a stain which gives only the marked differences. The examination showed that there were very few changes in the tissues on this ration. The heart, pancreas, liver and testes remained normal in most cases. 81ight changes were found in the kidney and spleen. Congestion and chronic inflammation was frequently found, indicating, in all probability, a secondary infection, although an effort was made to discard without microscopical examination all those which gave evidence of infections of the respiratory tract. The spleen showed very slight changes. There was congestion with frequent dilation of venous sinuses. In some the congestion was so marked as to mask the structure. Necrosis or degeneration of splenic reticulum was not observed. There seemed to be no relationship between the degree of congestion and the duration of the experiment. The main finding in the kidney was cloudy swelling of the parenchyma of the collecting tubules.

This was more marked in the tissues of the second generation born on the ration. An albuminous precipitate was present in the tubules of some. Congestion also was found. In places the cells of the tubules appeared skeletonized, and the glomerular tufts slightly shrunken. The liver appeared normal in all cases. Necrotic and degenerative changes were absent. In one lot there was a total absence of red blood cells. Otherwise the structure was normal.