522 W. W. SWINGLE 



The writer thought that by repeating Gudernatsch's thyroid 

 feeding experiment and noting the effect of accelerated meta- 

 morphosis on the gonads of young larvae, perhaps some new 

 light might be shed upon the problem of the germ gland-thyroid 

 relationship. 



LITERATURE 



A great many researches dealing with the thyroid gland have 

 appeared in the past few years, but few of them are concerned 

 directly with the relation of the thyroid to the germ glands and 

 cells. 



Long ago J. F. Meckel advanced a theory that the thyroid 

 gland is intimately associated physiologically with the female 

 organs of generation. This view is based upon the fact that 

 the thyroid of women is larger than that of men, and that it in- 

 creases in size during menstruation, deflorescence and pregnancy. 



Hofmeister, who investigated the problem of the relation of 

 the thyroid to growth and development, extirpated the glands 

 of young rabbits. Among other pathological changes which 

 resulted, were certain degenerative processes in the reproductive 

 glands; the ovaries, for instance, invariably revealed premature 

 maturity of many of the follicles. 



Another investigator, Jeandelize, has shown that in male 

 animals whose thyroid had been removed, there is imperfect 

 development of the testes. 



v. Eiselberg found that in sheep whose thyroids had been 

 removed at the age of ten days, there was an inhibition of the 

 growth of the testes. This same author also operated upon goats 

 three weeks after birth, and some months later observed arrested 

 development of the sexual glands. 



Lanz observed in his investigations, that after thyroidectomy 

 had been performed upon hens, there resulted imperfect activity 

 of the sexual glands. Such fowl laid very few eggs, and these 

 were abnormally small and covered with very thin shell. This 

 author states that the laying capacity of these thyroidless hens 

 may be increased by feeding with thyroid gland. 



