20 Messrs. E. A. Schafer and K. Mackenzie. [Mar. 7, 



luteum extract made up in the proportion of 1 part of the fresh tissue to 

 10 parts of Singer's solution. One such result is shown in fig. 2, A. The 

 active substance of the corpus luteum is probably not the same as that 

 obtained from the pituitary, for its galactagogue action is unaccompanied by 

 the same general rise of blood-pressure; indeed, there is usually a fall of 

 a more or less decided character. As with the pituitary material, the 

 galactagogue substance of the corpus luteum is not yielded to absolute 

 alcohol, nor destroyed by contact with alcohol (at least for a short time) 

 nor by repeated boiling. And, as with pituitary extract, a repeat dose is 

 usually less effective as compared with the first dose ; the amount of milk 

 formed under its influence is often insufficient to cause the secretion to flow 

 from the nipple, although secretion may be apparent when the exudation 

 method is adopted. A second effect is, however, distinct in fig. 2, B. 



"Tig. 2. — Eecords of milk-flow from a nipple of a lactating cat as the result of the intra- 

 venous injection of 5 c.c. of Binger's solution extract of corpus luteum from sheep's 

 ovary. Two such injections were given. In the record of the first (A) six drops are 

 shown ; in that of the second (B) five drops. Signal and time tracings as in fig. 1. 



In order to produce the galactagogue effect, it is not necessary to employ 

 a lactating animal. In one instance we obtained a free flow of fluid — of 

 serous appearance — from the incised mamma of a cat, apparently virgin, and 

 not fully grown. This is illustrated in the tracing which is shown in fig. 3, 

 which is from a small cat, weighing 2^ kilogrammes and rather more than 

 three parts grown. The mammary glands were very small and little 

 developed, and confined to the neighbourhood of the nipples. The 

 fluid which exuded from the incised gland was led by a wet cotton wick 

 over a drop-recorder and the drops were marked in the usual way by electro- 

 magnetic signal. Prior to the injection (of the corpus luteum extract) no flow 



