892 PHYSIOLOGY OF DIGESTION AND SECRETION. 



infantilism, together with increased tolerance to carbohydrates. 

 These effects are attributed to a hyposecretion of the posterior lobe. 



The Functions of the Pituitary Body. It seems evident from the 

 above brief statement of the results of experiments and clinical 

 observations that the pituitary body is essential in some way to 

 normal body-metabolism, and moreover that the anterior and pos- 

 terior lobes exercise different functions.* The differentiation in 

 function between the two parts or two glands cannot be made 

 completely at present, but so far as our knowledge goes it would 

 seem that the anterior lobe furnishes a secretion that stimulates 

 the growth of the skeleton and possibly the connective tissues in 

 general, and in addition exercises some deeper influence on metabo- 

 lism of an unknown but essential nature. The posterior lobe, on 

 the contrary, furnishes one or several hormones that have a stimu- 

 lating effect upon several processes the tone of plain muscle, the 

 secretory activity of several glands, and the process of glycogeno- 

 lysis. In addition, this portion of the gland shares with others of 

 the ductless glands (thymus, cortex of the adrenal glands) a regu- 

 lating influence upon the normal development of the reproductive 

 organs. Its influence in this respect resembles and may be con- 

 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 restrains 

 the development of the reproductive glands, but it should be 

 noted that this conclusion is not well supported by experimental 

 * Consult Schafer, "The Endocrine Organs," London, 1916. 



