890 PHYSIOLOGY OF DIGESTION AND SECRETION. 



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 all or most of the involuntary muscles in the body. The in- 

 testine, bladder, and uterus are all made to contract, and this ef- 

 fect is perhaps especially marked in the case of the uterine mus- 

 cle, so much so in fact that it has been proposed to use such ex- 

 tracts in obstetrical practice to promote the contractions of the 

 uterus. While the epinephrin acts mainly at least on plain muscle 

 innervated by the sympathetic autonomies and gives contraction or 

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

 hormone 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, f They cause a distinct diuresis by an effect on the kidneys; 

 they act as a galactogogue to the mammary glands when in func- 

 tional activity, and it is stated that they accelerate the rate of 

 formation of cerebrospinal liquid. Lastly, these extracts influence 

 the general metabolism, particularly in regard to the carbohydrates. 

 Like the epinephrin, they cause a glycosuria, and apparently in the 

 same way, that is, by accelerating the process of glycogenolysis in 

 the liver. 



Extracts of the Anterior Lobe. In marked contrast to the effects 

 obtained from the posterior lobe, extracts of the anterior lobe when 

 injected yield no immediate results. As will be seen below this lobe 

 undoubtedly furnishes an important secretion, but the specific 



* Howell, "Journal of Experimental Medicine," 3, 245, 1898; also Schafer 

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



t Schafer and Herring, "Philosophical Transactions Royal Society/' 

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

 Med.," 8, 28, 1910-11; Weed and Gushing, "American Journal of Physiology," 

 36, 77, 1915. 



