884 PHYSIOLOGY OF DIGESTION AND SECRETION. 



nected with the activity of the interstitial tissue within the sub- 

 stance of the ovary or testis. 



The Pineal Body (Epiphysis Cerebri) . This small body 

 projects from the roof of the third ventricle and embryologically 

 develops as an outgrowth from this vesicle of the brain. In early 

 life it has a glandular structure which seems to reach its greatest 

 development at about the seventh year. After this period and 

 particularly after puberty it undergoes a process of involution 

 during which the glandular structure gradually disappears and its 

 place is taken by fibrous tissue. The gland is noteworthy also for 

 the appearance of calcareous concretions, the so-called brain sand, 

 which may appear even in early life. Intravenous injections of ex- 

 tracts of this gland seem to cause a distinct fall in blood-pressure, 

 indicating the presence of a depressor substance. On the patho- 

 logical side it is stated that in young children invasion of the gland 

 by pathological growths results in distinctive effects. Under such 

 conditions there is presumably a diminished activity of the gland, 

 and the results observed are an accelerated development of the 

 reproductive organs, with an attending mental precocity and an 

 increased growth of the skeleton. The inference made, therefore, 

 from these observations is that in the young child the gland fur- 

 nishes a secretion which inhibits growth and particularly restains 

 the development of the reproductive glands, but it should be 

 noted that this conclusion is not well supported by experimental 

 evidence. Total extirpation of the gland gives no decisive effect 

 upon the animal (Dandy). 



Organs of Reproduction. Some of the earliest work upon the 

 effect of the internal secretions of the glands was done upon the 

 reproductive glands, especially the testis, by Brown-Sequard.* 

 According to this observer, extracts of the fresh testis when in- 

 jected under the skin or into the blood may have a remarkable 

 influence upon the nervous system. Mental and physical vigor, 

 and the activity of the spinal centers, are greatly improved, not 

 only in cases of general prostration and neurasthenia, but also in 

 the case of the aged. Poehl asserts that he has prepared a sub- 

 stance, spermin, to which he gives the formula C 5 H 14 N 2 , which 

 has a very beneficial effect upon the metabolism of the body. 

 He believes that this spermin is the substance that gives to the 

 testicular extracts prepared by Brown-Sequard their stimulating 

 effect. He claims for this substance an extraordinary action as a 

 physiological tonic, but it cannot be said that his assertions have 

 been corroborated by later work. Zothf and also Pregel seem to 



* "Archives de physiologie normale et pathologique," 1889-92. 

 t "Pfliiger's Archiv f. die gesammte Physiologie," 62, 335, 1896; also 69, 

 386, 1897. 



