THE PITUITARY AND THE THYROID 



tone, and pyridine. Purified preparations of the hormone are 

 readily adsorbed. Aqueous solutions of the hormone stimu- 

 lating the mammalian thyroid are said to lose their activity 

 after boiling, whereas those stimulating the amphibian thy- 

 roid are said to be little affected; the difference may depend 

 upon differences in experimental conditions (pH of solution, 

 purity of extract, dosage, etc.). There is more or less satis- 

 factory evidence that the thyrotropic hormone can be sepa- 

 rated from the growth-promoting, gonad-stimulating, and 

 lactogenic hormones of the anterior pituitary (also see Riddle, 

 Bates, and Dykshorn, 1933; Greep, 1933, 1935; Guyenot and 

 others, 1934; and Wallace, 1934). 



In the normal animal, the thyroid-stimulating hormone 

 appears to be specifically elaborated by the anterior pitui- 

 tary. Extracts of kidney, testis, placenta, and muscle cause 

 no thyroid stimulation (Aron, 1930). Aron stated that one 

 milligram of anterior pituitary was more effective than the 

 equivalent of 10 g. of any of the control tissues mentioned 

 above. Extracts or suspensions of placenta were found to 

 cause no thyroid stimulation (Geyer, 1933; and Greep, 1933) 

 or "stimulation" only in the female (Collip, Thomson, and 

 Selye, 1933). According to Geyer, urine from a case of hy- 

 datidiform mole as well as a suspension of the tumor tissue 

 caused marked thyroid stimulation. Heyl (1934) found that 

 ascorbic acid stimulated the thyroid but beheved that ascor- 

 bic acid was more readily oxidizable than the true hormone. 

 Nearly all investigators agree that the gonad-stimulating 

 principle of pregnancy-urine (prolan) does not stimulate the 

 thyroid (Aron, 1931; Janssen and Loeser, 1931; Paal, 1931; 

 Verzar and Wahl, 1931; Loeb, 1932; Doderlein, 1933; Greep, 

 1933; and Junkmann, 1934). All who have investigated the 

 effect of prolan on the basal metabolism of man or animals 

 have found that it does not elevate the basal metabolism; 

 some workers, indeed, reported that prolan depresses the 

 metabolism. 



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