5 io TEXT-BOOK OF PHYSIOLOGY 



by a decline in physical vigor, inactivity and a cessation of sexual activity. 

 From the foregoing facts it is apparent that these organs are engaged in the 

 production of an internal secretion which influences favorably the growth, 

 development, and general vigor of the entire body. 



Extracts of the testicles have been prepared and injected into the body 

 in advanced years, with a view of reestablishing the former condition of 

 body vigor. Experiments of this character were made originally by Brown- 

 Sequard on himself and reported that his general health, his muscular power 

 and mental activity were much improved. These results have not received 

 general confirmation. 



The ovaries are also regarded as glands for the production of an internal 

 secretion, as well as for the production of characteristic reproductive ele- 

 ments. The ovary possesses in the epithelium of the Graanan follicles an 

 apparatus for the development of the ova, and in the cells of the intervening 

 stroma the so-called interstitial cells an apparatus for the production of 

 an internal secretion which is poured into the blood and influences not only 

 the development of sexual organs but influences favorably the development 

 of the secondary sexual characters as well as the body as a whole. 



The removal of the ovaries of human beings early in life is an operation 

 that is not often performed and hence it is difficult to state the results that 

 might arise. Their removal in certain animals leads to an atrophy of the 

 uterus, and in addition, to a failure of development of secondary sexual 

 characters. Menstruation does not occur and the body does not reach matu- 

 rity. The removal of the ovaries in adult life results in a cessation of men- 

 struation, and the appearance of a variety of disorders of a bodily and mental 

 character. Similar phenomena are frequently observed at the menopause, 

 when the ovaries undergo degenerative changes. The administration of 

 extracts of the ovaries oophorin tablets is claimed to relieve some of the 

 symptoms following the 'removal of the ovaries or occurring during the 

 menopause. The transplantation of an ovary into the wall of the uterus or 

 into the broad ligament after ovariotomy in women has, even after the lapse 

 of two years, reestablished menstruation and awakened sexual desire. From 

 facts such as the foregoing it has come to be believed that ovaries also produce 

 an internal secretion which has a marked influence on the body and 

 mental states of women and mammals generally. 



The Thymus. The thymus is presumably a gland of internal secretion, 

 but the evidence at hand is not very convincing. Whether the thymus 

 produces and discharges a specific material into the blood at the time of its 

 greatest development, i.e., during the latter part of intra-uterine life and 

 during the first two years or longer after birth, and which favorably 

 influences growth and development, there is no means of determining 

 with present methods of investigation. The thymus gradually degener- 

 ates and disappears as the period of puberty is reached. 



The Pineal Body or Conarium. This body projects from the roof of the 

 third ventricle and occupies the space between the superior quadrigeminal 

 bodies. It is regarded as a vestigial remnant of a primitive dorsal eye 

 of some ancestral vertebrate and not an ingredient of the human brain. 

 In some lizards the pineal body- is an eyelike organ situated under the 

 integument. In its development it resembles the eye, but even in lizards 

 it has lost all visual functions. 



