752 FREDERICK S. HAMMETT 



solution. When the lead hydroxid filtrate was quickly evaporated without 

 the addition of silver nitrate a substance was obtained that after repeated 

 solution ki methyl alcohol and precipitation by anhydrous ether yielded 

 a crystalline product. This they consider to be the true base because of 

 its characteristic pharmacological reactions. Nevertheless, they failed 

 to report any chemical analysis of the compound. A recent study by 

 Fenger and Hull (1920) was unsatisfactory. 



The methods of manufacture of the commercial extracts of the pos- 

 terior lobe are not particularly complicated. One of them consists in ma- 

 cerating the finely ground tissue for four hours with a strongly diluted 

 solution of acetic acid at a temperature just below the boiling point of 

 water. The extract so obtained is filtered from the residual tissue till 

 clear, sterilized by passing through a Berkefield filter candle and put up 

 in suitable sterile containers for marketing. There is considerable loss 

 of active principle, as measured by the oxytocic reaction, during this 

 process. Adams (1917) made a study of the conditions leading to de- 

 struction of the active compound and found that the substance is de- 

 stroyed at the temperature of boiling water when the hydrogen-ion con- 

 centration is N" x 10- 5 but that the compound is stable at the greater 

 acidity of N x 10- 3 . From the fact that the rate of destruction proceeds 

 in a manner characteristic of a single substance decomposing according 

 to the law of a mono-molecular reaction, it is evident that the determina- 

 tion of the strength of posterior lobe extract on the basis of its oxytocic 

 effect represents an evaluation of a single substance and is valid for the 

 measurement of this principle. This substance may not be the pressor 

 compound. 



Inasmuch as the question has arisen whether or not the small amounts 

 of alcohol left in the syringe after sterilization destroy the physiological 

 activity of the extract Hamilton (1918) and Pittenger (1918) investigated 

 this possibility and found that the addition of reasonable amounts of 

 alcohol to the extracts caused no diminution in their activity. 



A.wayiny Posterior Lobe Extracts. There have been three main meth- 

 ods advocated for testing the pharmacological or therapeutic value of pos- 

 terior lobe extracts. The observations of Dale and Laidlaw (1912-13) 

 that extracts of the posterior lobe cause contraction of the isolated uterus 

 of the virgin guinea-pig was the starting point not only of the use of such 

 extracts in clinical practice, but also of the use of this tissue as a test- 

 reaaent for determining the strength of the extracts used. Although these 

 workers found that the application of equal amounts of the extract to 

 the same uterine segment caused an almost equal amount of contraction it 

 remained for Roth( ) (b) (c) (1913-14) to establish (3-iminazolylethylamin 

 hydrochlorid as the standard substance with which the activity of the 

 posterior lobo extracts could be compared, which standard has been ac- 

 cepted as the official method of the United States Pharmacopoeia. The 



