92 INTERNAL SECRETIONS OF THE OVARY 



to produce a reaction by mouth, while Laqueur, Hart, and de 

 Jongh (349) found a hundred times as much to be necessary. 

 Hannan (268) states that sixty times as much is needed orally 

 as subcutaneously. The fate of the hormone in the alimentary 

 canal does not seem to be known. It was naturally thought that 

 its destruction was due to the digestive enzymes, but this ex- 

 pectation does not seem to have been confirmed. Also, the 

 degrees of acidity and alkalinity normally found in the ali- 

 mentary canal can hardly be sufficient to destroy the hormone. 

 It is possible that the active substance passes through the tract 

 without being absorbed, but it has been found impossible to 

 detect the hormone in the faeces after heavy administration by 

 mouth. 



Siihcutaneous injection. Preparations are usually adminis- 

 tered by subcutaneous injection, but the behaviour of the 

 preparation after such administration varies very greatly 

 according to the chemical nature of the extract. Preparations 

 containing much cholesterol invariably cause granulation and 

 subsequent sloughing. In these cases where much inactive 

 matter is present, the absorption of the active substance can 

 hardly be very complete, and no accurate assay can be carried 

 out where this complication occurs. The fact that a large 

 injection of a relatively impure preparation will produce oestrous 

 symptoms for more than fourteen days seems to show that 

 absorption under such conditions is very slow. Since the dura- 

 tion of oestrous symptoms following injection probably depends 

 largely upon the rate of absorption, and therefore upon the 

 purity of the extract, it cannot be of any value in assaying the 

 activity of an extract. 



Intra-peritoneal injection. Intra-peritoneal administration 

 has not been found to have any advantages over subcutaneous 

 injection. Allen and Doisy (24) and Coward and Burn (146) 

 were unable to detect greater efficiency, and Evans and Burr 

 (184) even report an increased activity from subcutaneous 

 injection. 



Intra-venoiis injection. This type of administration has 

 hardly been possible with crude fat-soluble extracts, but the 

 comparative purity of the recent water-soluble preparations 

 may make administration direct into the blood stream a 



