io8 INTERNAL SECRETIONS OF THE OVARY 



restricted to the fluid centre, it seems probable that the 

 corpus luteum tissue does not elaborate the hormone. As 

 regards the ovary, therefore, it may be said that the liquor 

 folliculi of all mammals which have been examined contains this 

 hormone, as does the stromal tissue, but that the corpus luteum 

 contains it incidentally or doubtfully. 



Distribution in other animal tissues. It has been known for 

 a long time that the placenta contains large amounts of 

 oestrin. Eels (202) failed to find it before the second month 

 of pregnancy, but Allen, Pratt, and Doisy (25) found it in 

 placentae of the third month, and Eellner (191, 192), Herrmann 

 (292), Eraenkel and Fonda (218), Zondek and Brahn (661), 

 Frank and co-workers (229, 231), Allen, Doisy and co- 

 workers (23, 25, 167), Hartmann and Isler (281), Suzuki 

 (606), Zondek and Aschheim (651), Parkes and Bellerby (506), 

 Ceresoh (117), and Dickens, Dodds, and Wright (158) have 

 all found it at later stages. (Estrin has also been found in 

 the foetal membranes (25), amniotic fluid (506, 132, 93, 203), 

 and umbihcal cord (25), but extracts of the foetus itself have 

 given uniformly negative results (25, 167, 506). 



Various other body tissues have been examined either with a 

 view to ascertaining the distribution of oestrin in the body or 

 with a view to providing control experiments on the extrac- 

 tion of ovaries. Negative results have been obtained from 

 liver (230), brain (230), thymus (230), pancreas (167), 

 pituitary (538), adrenal (654), thyroid (651), spleen (654), and 

 muscle (503). 



Distribution in body fluids. Since it is obvious that the 

 hormone must pass from its site of origin to its site of activity 

 by way of the circulating blood, one would expect to be able to 

 detect its presence in the blood provided that sufftciently small 

 amounts could be recognized. Also, since its action is cyclic, it 

 might be expected that periodic variation in amount in the blood 

 could be demonstrated. Its presence in the blood of the non- 

 pregnant female has been shown by Loewe (408), Frank and 

 co-workers (225, 227), and Smith (574). Frank and co-workers 

 (223) found oestrin in the blood of the oestrous sow, and in the 

 human in amounts varying with the stage of the cycle. 

 According to these workers, it is present in greatest amount 



