qo INTERNAL SECRETIONS OF THE OVARY 



comparatively high temperatures, though the exact tempera- 

 ture at which destruction takes place appears to vary with the 

 nature of the impurities. Laqueur, Hart, and de Jongh (346) 

 found that their less pure preparations resisted up to 360° C, 

 but that the purified aqueous solution was inactivated at 

 170° C. 



Chemical cojistitution. Ralls, Jordan, and Doisy (524) found 

 that phosphorus was not present in active extracts, while 

 Laqueur, Hart, de Jongh, and Wijsenbeek (356) failed to find 

 nitrogen. This was confirmed by Wadehn (627) , who, in addition, 

 failed to find sulphur, and alcohol and amino groups. Laqueur, 

 Hart, and de Jongh (355) report the absence of histidine and 

 sulphur. 



Colour reactions. Laqueur, Hart and de Jongh (355) obtained 

 negative results with the Biuret and Diazo tests. Laqueur 

 (344), Dodds and co-workers (158) and Frank and his co-workers 

 (230) have obtained negative results with the Liebermann and 

 Burchard-Salkowski tests for cholesterol. 



Oxidation, bromination, hydrogenation. (Estrin is readily 

 destroyed by oxidation, undergoing slow inactivation from 

 atmospheric oxygen, and rapid destruction by oxidizing agents 

 such as potassium permanganate (166, 524) and phosphorus 

 pentachloride (230). Ralls, Jordan, and Doisy (524) state that 

 the hormone survives hydrogenation, but according to Giesy 

 (see Allen and Doisy, 21), it is inactivated by bromination. A 

 similar conclusion has been reached by Doisy and co-workers 

 (166, 524), and Frank and co-workers (230). This susceptibility 

 to bromination does not necessarily indicate the presence of a 

 double bond. 



Resistance to enzymes. Gastrin resists the lipases of plants 

 (166), of the pancreas, and of the liver (167). Laqueur, Hart, 

 and de Jongh (346) confirmed these facts on their water- 

 soluble products, which also showed resistance to pepsin. 



Saponification. Doisy, Ralls, Allen, and Johnston (167) 

 reported resistance to saponification by sodium ethylate and 

 this has been confirmed by many workers. Laqueur, Hart, and 

 de Jongh (344) boiled purified preparations with 26 '^^ KOH and 

 26% H2SO4 without causing destruction, and the same authors 

 (346) showed that it resisted 10 ",j KOH up to 170° C. Other 



