6 7 i 



Pineal Gland. Extracts of the pineal gland injected into the circula- 

 tion have no effect other than that due to the inorganic constituents 

 of the calcareous concretions or ' brain sand,' which are its character- 

 istic feature. Since in early life the organ has a glandular structure 

 which is later replaced by fibrous tissue, it has been supposed that it 

 may exercise some function in connection with growth. But so far 

 the physiology of the pineal body is practically a blank sheet, or, at 

 best, a budget of contradictory statements from which nothing certain 

 can be deduced. Thus in two of the most recent papers, each based 

 on a large number of careful experiments, one author concludes that 

 removal of the gland in male guinea-pigs is associated with hastened 

 development of the sexual organs, and in females with a tendency to 

 breed earlier than the normal controls (Horrax). The other observer 

 finds that feeding young guinea-pigs with pineal tissue from young 

 animals determines an earlier sexual maturity than normal, and in- 

 creases the rate of growth of the body (McCord) . 



The alleged influence of the invasion of the gland in young children 

 by pathological growths in accelerating the development of the skeleton 

 and reproductive organs, which has been supposed to indicate that it 

 normally exerts a restraining or regulative influence on this develop- 

 ment, is at present purely fanciful. 



Kidney. The experiments of Bradford, which seemed to indicate 

 that the kidney, in addition to its function as an excretory organ, plays 

 an important, and indeed indispensable, part in protein metabolism, 

 possibly by forming something of the nature of an internal secretion, 



Fig. 218. Effect of Bone-Marrow on Blood-Pressure. Intravenous Injection of 

 Saline Extract Vagi Intact. The uppermost line is a signal trace showing the 

 time and length of injection. Below this is the record of the respirat ^ry move- 

 ments, and lowest the blood-pressure tracing. To be read from leU to right. 



have not been confirmed. He stated that, when the half or two-thirds 

 of one kidney and the whole of the other have been removed from a 

 dog by successive operations, death ensues, although the quantity both 

 of water and urea excreted by the fragment of renal substance that 

 remains is far above the normal. In spite of the increased elimination 

 S^A th H at f subs , tance , was ^d to accumulate in the tissues.Towing 

 that the destruction of protein was increased a conclusion which 

 seemed to derive support from the wasting of the animal. It has since 

 been shown that an increased output of nitrogen is not of constant 

 occurrence and only takes place under the same conditions aT^ 

 starvation (p. 603). As a matter of fact, the animals waste and d 



