320 INTERNAL SECRETIONS 



on the sex characters. But the observations of the different 

 investigators disagree very considerably. This is easy to 

 understand if one takes into consideration the fact that the 

 chemical nature of the various extracts must differ greatly 

 according to the special technical methods of preparation. 

 The disagreement is so great that we find one authority 

 attributing to the extract of the gland the capacity for raising 

 the blood pressure, and another describing precisely the opposite 

 effect. Biedl (1913, p. 292 of Vol. II.) has strongly criticised 

 all these experiments, pointing out that very probably the 

 effects obtained by these extracts, which are considered as 

 specific of sexual hormones, are often nothing else than effects 

 which can be obtained with extracts of any organ. Possibly 

 profound chemical alterations take place when an extract is 

 made, and we must suppose that the extract contains different 

 products derived from the common proteins of the respective 

 organ. It is known that these derivatives of proteins may 

 have toxic effects on the organism. These products are 

 characteristic not of certain proteins, but of proteins in general. 

 The severe verdict of Gley (19 14, p. 43) on the experiments 

 concerning the effects of organic extracts in general seems to be 

 justified for the experiments made with extracts from the 

 sex glands: "presque tons les travaux faits depuis quinze ans 

 sur cette question I'ont ete avec une methode, non pas absolu- 

 ment defectueuse, mais incomplete, done insuffisante."^ 



It cannot be denied that it is possible to produce with 

 extracts from the sex glands some specific effects characteristic 

 of these glands in situ, as was shown in Chapter III., especially 

 for the frog. Similar specific effects of sexual hormones have 

 sometimes been obtained also by injection of these extracts into 

 birds and mammals. The reappearance of the turgor of the 

 comb and of the sexual instincts after injection, as in the 

 experiments of Pezard (1911), may be mentioned here. We 

 have noted also the successful experiments of Bouin and Ancel 

 (1906) on injected guinea pigs, and we shall describe in this 

 chapter similar experiments by Fellner and Herrmann on 

 rabbits. But on the other hand one must never forget that 

 the effect of an extract, as already remarked, varies much 

 according to the rnethods used for its preparation, and this is 



^See also the new edition of Biedl's "Internal Secretion'' (1922); the 

 book of Maranon (1922, ch. XI.) may also be consulted here. 



