650 INTERNAL SECRETION 



removal of both kidneys or ameliorate them when they have already 

 anpeared. f 



(The spleen jfloes not produce an internal secretion necessary to life, 

 for it can b^removed both in animals and in man, not only without 

 causing death, but often without the development of any serious 

 symptoms.! Its blood-forming and blood-destroying functions (p. 22) 

 are taken an by other structures (particularly the red bone-marrow), 

 but the formation of the bile-pigment is interfered with, and its amount 

 reduced by more than 50 per cent. (Pugliese). The production of 

 trypsinogen by the pancreas is also said to be diminished, whereas if 

 an extract of spleen be injected into the circulation of an animal 

 deprived of its spleen, the amount of trypsinogen is increased, lit has, 

 therefore, been supposed that the spleen forms a substance (protryp- 

 sinogen) which, passing into -the blood, is taken up by the pancreas and 

 elaborated into trypsinogen |p. 405). 



fThe salivary glands may f>e extirpated without any sensible change 

 being produced in the normal metabolism. There is evidence, how- 

 ever, that the secretion of the gastric juice is diminished} It has been 

 supposed that this may be due to the absence of a hormone (p. 398) 

 normally produced in the salivary glands. A temporary increase in 

 the gastric secretion is caused when extracts of the glands of normal 

 dogs are injected into the veins or into the peritoneal cavity of dogs 

 deprived of their salivary glands (Hemmeter). 



f Extracts of nervous tissue (sciatic nerve, white matter of brain, and 

 spinal cord, but especially grey matter of brain) cause, on injection into 

 the veins, a decided fall of arterial blood-pressure, which soon passes 

 off, and can be renewed by a fresh injection! The fall of pressure is 

 due to direct action upon the bloodvessels of ^, depressor substance in 

 the extracts, and not to the action of vaso-motor nerves. It can be 

 obtained after. section of the vagi. 



(Extracts of muscular tissue also cause a distinct though transient 

 fall of pressure) but not so great a fall as in the case of extracts of 

 nervous tissue. Saline decoctions of other tissues (testis, kidney, 

 spleen, pancreas, liver, mucous membrane of stomach and intestine, 

 lung, and mammary gland) all produce a fall of blood-pressure (Osborne 

 and Vincent). The same is true of bone-marrow (Brown and Guthrie; 

 Figs. 208, 209). It must be repeated that there is no evidence that 

 these depressor substances are specific internal secretions in the same 

 sense as adrenalin. 



