884 PHYSIOLOGY OF DIGESTION AND SECRETION. 



Steinach states that such an animal is sought by the male as 

 though it were a true female. It would follow from these experi- 

 ments that the internal secretion of the interstitial cells in the ovary 

 and in the testis has each its specific influence in guiding the de- 

 velopment of the sexual characteristics, one causing the formation 

 of male, the other of female characteristics. Many experiments 

 and observations indicate that the internal secretions of the ovaries 

 and testes are important, not only as regards so-called secondary 

 sexual characteristics, but also in regard to the body-metabolisms in 

 general. Some evidence for this general view is found in the 

 functional relationship that appears to exist between these organs 

 and other ductless glands, such as the cortical portion of the 

 adrenal gland and the posterior lobe of the hypophysis. The 

 nature of these reciprocal relationships cannot be explained at 

 present, but it may be assumed that they are concerned with 

 modifications of the nature of some of the processes of body- 

 metabolism and that the effects produced depend upon definite 

 hormones or internal secretions. Further evidence of the same 

 character may be found in observations like the following: 



In gynecological practice it has been observed that complete 

 ovariotomy with its resulting premature menopause is often 

 followed by distressing symptoms, mental and physical. In 

 such cases many observers have reported that these symptoms 

 may be alleviated by the use of ovarian extracts. Similar results 

 have been reported upon the lower animals. After complete ovari- 

 otomy a condition of "heat" may be reproduced by grafting ovarian 

 tissue, * and several observers agree in stating that removal of the 

 ovaries in young animals prevents the normal development of the 

 uterus, while in adult animals it causes the organ to undergo a 

 fibrous degeneration (see section on Reproduction). In the 

 natural menopause, as well as in the premature menopause follow- 

 ing complete removal of the ovaries, 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 charac- 

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

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

 the effects described above may be referred mainly to the internal 

 secretion of the interstitial cells of the ovaries, other facts indicate 

 that other elements in the gland may also furnish a specific secre- 

 tion. 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 chem- 

 * Marshall and Jolly, "Physiological Transactions," B. cxxvii, 99, 1905. 



