804 PHYSIOLOGY OF DIGESTION AND SECRETION. 



"heat" may be reproduced by grafting ovarian tissue * (see section 

 on Reproduction). In the natural menopause, as well as in the 

 premature menopause following operations, it is a frequent, though 

 not invariable, result for the individual to gain noticeably in weight. 

 An effect of the ovaries on general nutrition is indicated also by 

 the interesting fact that in cases of osteomalacia, a disease char- 

 acterized by softening of the bones, removal of the ovaries may 

 exert a favorable influence upon the course of the disease. These 

 indications have found some experimental verification in a research 

 by Loewy and Richter f made upon dogs. These observers found 

 that complete removal of the ovaries, although at first apparently 

 without effect, resulted in the course of two to three months in a 

 marked diminution in the consumption of oxygen by the animal, 

 measured per kilogram of body- weight. If now the animal in this 

 condition was given ovarian extracts (oophorin tablets) , the amount 

 of oxygen consumed was not only brought to its former amount, 

 but considerably increased beyond it. A similar result was obtained 

 when the extracts were used upon castrated males. The authors 

 believe that their experiments show that the ovaries form a specific 

 substance which is capable of increasing the oxidations of the body. 

 In addition to the internal secretion of the ovaries which is respon- 

 sible for the phenomenon of menstruation, other similar secretions 

 have been assumed to account for changes connected with the 

 process of reproduction. Thus the implantation of the fertilized 

 ovum in the uterine mucous membrane and the development of 

 the placenta have been supposed to be effected through the agency 

 of some chemical stimulus arising in the cells of the corpus luteum. 

 So also the development of the mammary glands during pregnancy 

 is attributed to the action of a hormone formed in the tissues of 

 the fetus itself (see section on Reproduction). 



Pancreas. The importance of the external secretion, the pan- 

 creatic juice, of the pancreas has long been recognized, but it was 

 not until 1889 that von Mering and Minkowski J proved that it fur- 

 nishes also an equally important internal secretion. These observers 

 succeeded in extirpating the entire pancreas without causing the 

 immediate death of the animal, and found that in all cases this 

 operation was followed by the appearance of sugar in the urine in 

 considerable quantities. Further observations of their own and of 

 other experimenters have corroborated this result and added a num- 

 ber of interesting facts to our knowledge of this side of the activity 

 of the pancreas. It has been shown that when the pancreas is com- 

 pletely removed a condition of glycosuria inevitably follows, even 



* Marshall and Jolly, "Philosoph. Transactions," B. cxcviii., 99, 1905. 

 t Loewy and Richter, " Archiv f. Physiologie, " 1899, suppl. volume, p. 174. 

 J Minkowski, "Archiv f. exper. Pathologic u. Pharmakologie, " 31, 85, 

 1893. 



