THE PITUITARY BODY 



described. A great number of solvents have been used, such 

 as aqueous solutions of acids (e.g., acetic acid) and alkalis 

 (e.g., I per cent NH4OH, 50 per cent pyridine), aqueous solu- 

 tions of higher alcohols (6 per cent butyl alcohol, 3 per cent 

 amyl alcohol), aqueous solutions of ethyl alcohol or acetone 

 (50-60 per cent) containing ammonia (2-4 per cent), and 

 glycerine. For subsequent purification, methods too numer- 

 ous to describe in any detail have been used. The reader is 

 referred to the authors Hsted above. 



The cruder the preparation, the greater is its stability 

 either in solution or in the form of a solid. The hormone (or 

 hormones) is destroyed or inactivated by boiling in aqueous 

 solution (if perfectly dry, however, it is not affected by a tem- 

 perature of 100° C. for hours). Inactivation or destruction of 

 the hormone is also said to occur in the presence of a polypep- 

 tidase or of trypsin. The preparations so far made do not di- 

 alyze through parchment or collodion; some have thought 

 that the hormone(s) is a polypeptide with a molecular weight 

 of 800-900. The hormone(s) is ordinarily rendered insoluble 

 by the addition of a sufficient amount of a protein precipitant. 



The assay of the gonadotropic hormone{s) of the anterior 

 pituitary. — In an earlier section of this chapter reference was 

 made to difficulties in the performance and interpretation of 

 accurate assays of gonadotropic hormones. Here an effort 

 will be made to discuss briefly the different methods by means 

 of which various authors have attempted to express quantita- 

 tively the gonadotropic potency of implants or extracts. The 

 following methods have been suggested: 



1. The production of ovulation in the toad. 



2. The stimulation of the growth of the immature pigeon's testis. 



3. The production of ovulation in the adult rabbit in oestrus. 



4. The stimulation of the growth of follicles and/or the formation of corpora 

 lutea in the ovaries of immature or adult mice and rats. 



To what extent is the amount of the same hormone (or hor- 

 mones) measured by these various methods? This question 



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