SECRETION OF THE DUCTLESS GLANDS. 879 



gland have taken the two usual directions, namely, a study of the 

 effects of removal and a study of the effects of extracts, and obser- 

 vations of this character have been made upon this gland as a 

 whole and upon the anterior and posterior lobes taken separately. 



Extracts of the Posterior Lobe. — Extracts of this lobe contain ma- 

 terial from both the pars nervosa and the pars intermedia, but on 

 the evidence stated above it may be assumed that the results ob- 

 tained are attributable in reality to the pars intermedia, which has 

 a glandular structure and is responsible for the hyaline material 

 found in the nervous part. When extracts of the posterior lobe 

 are injected into the circulation several distinct results have been 

 observed to follow. In the first place there is a characteristic effect 

 on the circulation— the heart-rate is slowed and the blood-pressure 

 is raised. Both effects are less marked than in the case of epi- 

 nephrin, but they persist for a longer time.* Further examination 

 has shown that the extracts seem to exercise a stimulating effect 

 on most of the involuntary muscles in the body. The intestine, 

 bladder, and uterus are all made to contract, and this effect is 

 especially marked in the case of the uterine muscle. The marked 

 stimulating effect upon the uterine musculature is referred to 

 frequently as the oxytocic activity of the extracts. While 

 epinephrin acts mainly at least on plain muscle innervated by 

 the sympathetic autonomics and gives contraction or relaxation 

 according as the nerve-fibers are motor or inhibitory, the hor- 

 mone from the posterior lobe of the pituitary gland appears to 

 act directly on the muscle and to cause contraction or increased 

 tone in all cases. In addition to this effect on plain muscle the 

 extracts have a stimulating action on several kinds of glandular 

 tissue, t They cause a distinct diuresis by an effect on the kid- 

 neys; they act as a galactagogue to the mammary glands when in 

 functional activity, and it is stated that they accelerate the rate 

 of formation of cerebrospinal liquid. The effect upon the secre- 

 tion of the mammary gland is explained usually on the view that 

 the extracts stimulate the plain musculature in the ducts and 

 alveoli, and thus cause the ejection of milk already formed. 

 According to this explanation the extracts do not act as a true 

 galactagogue, that is, they do not stimulate chrectly the milk- 

 secreting cells. 



The diuretic action of the extracts, first discovered by Schiifer, 



* Howell, "Journal of Experimental Medicine," 3, 24.5, 189S; also Schiifer 

 and Vincent, "Journal of Physiology," 25, 87, 1899. 



t Schiifer and Herring, "Philosophical Transactions Royal Society," 

 London, B, 199, 1; Ott and Scott, "Proceedings Society of Exp. Biol, and 

 Med.," S, 28, 1910-11; Weed and Gushing, "American Journal of Physiology," 

 36, 77, 191.5. 



