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considered that the condition was really associated with a deficiency of 

 thyroid secretion although the thyroids were enlarged. Bircher also 

 described acceleration of the development of the bony skeleton. 



Utter strom (21) in 1910 fed rabbits with thyroid and described a 

 resulting delay in the involution of the thymus. 



Iscovesco (13) in 1913 claimed to have isolated from thyroid tissue an 

 ether-soluble material which, injected repeatedly into rabbits, produced 

 remarkable effects. Iscovesco noted hypertrophy of the suprarenals in 

 both sexes, of the ovaries and uterus in the female, and of the testes in 

 the male. The spleen was slightly increased in size, the heart more 

 enlarged in males than in females, the kidneys hypertrophied in males 

 only. The growth of the body as a whole was greatly accelerated in 

 young rabbits, but only up to a certain age, after which administration of 

 the ether-soluble material caused actual loss of weight. In this connexion 

 the results obtained by Gudernatsch (6) are interesting. Gudernatsch 

 found that the macroscopic changes of differentiation in the tadpole are 

 greatly accelerated by even very small amounts of thyroid administered as 

 food. Growth is, however, checked, and the tadpoles rarely survive the 

 accelerated metamorphosis thus produced. 



Livingston (17) in 1914 showed that the hypertrophy of the pituitary 

 body which is known to follow thyroidectomy in rabbits is prevented by 

 feeding the animals with thyroid subsequent to operation. 



Kojima (16) in 1916 described hypertroph}" of the pancreas, the 

 occurrence of numerous mitotic fio;ures in the nuclei, and alterations in 

 the granules of the cells of the pancreas as the result of thyroid-feeding. 



The author (9) (10) in 1916 confirmed the results obtained by E. R. 

 Ho skins on the suprarenals, and found that small doses of thyroid pro- 

 duce hypertrophy of the suprarenals and an increase in their adrenalin 

 content both in the cat and in the white rat. Hypertrophy of the heart 

 was noted in the rat, and in a communication given to the physiological 

 section of the British Association at Newcastle in September 1916 figures 

 were shown which demonstrated that many other organs are affected, the 

 suprarenals, heart, and kidneys being especially subject to hypertrophy as 

 the result of thyroid-feeding. Further observations were in progress when 

 a very complete paper on the subject appeared by E. R. Hoskins (11). 

 Hoskins fed white rats with small doses of thyroid, thymus, pituitary, 

 and pineal body. The chief changes occurred in the thyroid-fed groups. 

 Compared with normal control animals of similar sex and of the same 

 litter, the thyroid-fed rats showed hypertrophy of the suprarenals, heart, 

 kidneys, alimentary canal including pancreas and mesentery, liver, and 

 spleen. In males the testes were somewhat increased in size, and in 

 females the ovaries. The pineal body showed no appreciable changes, the 

 thyroids were rather smaller, and there was some delay in growth of the 

 pituitary body in females. There was no constant change in the thymus. 

 Hoskins also investigated the head, body, cartilaginous skeleton, integu- 



