I.—PHYSIOLOGY I51 
others believe that prolan is not the true gonadotropic hormone. It is 
termed by Collip the A.P.L. or anterior pituitary-like substance, and is 
probably activated by the true gonadotropic hormone of the pituitary. 
It has long been known that removal of the anterior lobe of the pituitary 
results in rapid atrophy of the gonads, male or female. 
Extracts of the anterior lobe exert a similar influence upon the thyroids. 
Removal of the anterior lobe is followed by atrophic changes in them, 
while the injection of suitable extracts leads to their hypertrophy, even in 
the hypophysectomised animal. Loeb and Aron independently ascer- 
tained that extracts of anterior lobe produce in the guinea-pig hyperplasia 
of the thyroids, exophthalmos and other changes similar to those found 
in Graves’ disease. Shockaert has obtained striking results of the same 
nature in young ducks, and Houssay and others have produced them in 
various animals. It has been shown that exophthalmos may be caused 
by the injection of suitable extracts, even after removal of the thyroids. 
Marine has obtained exophthalmos by the use of methyl cyanide, and 
looks for its cause in the lessened oxidation acting through the dien- 
cephalon upon the pituitary body and the sympathetic system. Graves’ 
disease appears to be a syndrome in which the pituitary body and the 
diencephalon play an important part. 
The thyrotropic hormone has been prepared in a state of considerable 
purity, but it is not known from which type of cell it arises. Anderson 
and Collip have noted that repeated injections of this preparation bring 
about some immunity to its actions. 
Houssay and Sammartino have noted atrophic changes in the para- 
thyroids of dogs after removal of the anterior lobe, and Anselmino and 
Hoffmann have produced enlargement of these bodies by the injection of 
extracts of the lobe. Other workers have also obtained evidence of a 
parathyrotropic hormone in the anterior lobe. 
Removal of the anterior pituitary sets up atrophic changes in the cortex 
of the suprarenals, and Evans has shown that this can be prevented by 
the use of suitable extracts of the lobe. Houssay finds that the zona 
fasciculata and zona reticularis are the parts mainly affected. There is 
no change in the structure of the medulla or in its content of adrenaline. 
Collip has succeeded in separating the adrenotropic hormone from the 
others. 
Riddle and Bates have prepared a hormone, prolactin, from the anterior 
lobe which induces lactation in the fully developed mammary gland, 
growth and functioning of the crop-gland in pigeons, and brings about 
broodiness and the inhibition of ovarian function in fowls. 
Harvey Cushing and his co-workers have drawn attention to the changes 
in carbohydrate metabolism which are exhibited by patients and by 
experimental animals in hyper and in hypo-pituitary states. Houssay 
and Magenta found that after removal of the pituitary body dogs are 
especially sensitive to insulin, and become rapidly hypoglycemic. 
Houssay and Biasotti showed that the glycosuria following pancrea- 
tectomy can be prevented in toads by removal of the pituitary body. 
Somewhat similar results were obtained in dogs. Removal of the 
pituitary diminishes the glycosuria caused by pancreatectomy, and dogs 
