278 



Herring 



saccus vasculosus, jiiid extracts of the lobi inferiores, bring about a large 

 fall of blood-pressure ; the effects are similar to those seen after injection 

 of extracts of central nervous system in general. There seems to be 

 nothing in the infundibular region of the brain of the skate which is com- 

 parable in the action of its extract with the posterioi- lobe of the pituitary 

 body of nuuninals, birds, and bony fishes. 



Conclusions and Summary. 



In mammals, birds, and bony tishes the pituitary body consists of two 

 lobes, an anterior or epithelial which has the structure of a gland secreting 

 into blood-vessels, and a posterior composed of nervous tissue more or less 

 surrounded and invaded by epithelial cells of the pars intermedia. The 

 posterior lobe may also furnish secretion into blood-vessels, but its arrange- 



FiG. 8. — Effect of the injection into the jugular of a cat of 5 c.c. of an extract of tlie 



saccus vasculosus of the skate. (5 glands in 20 c.c. llinger.) 



There is a transient fall of Vilood-pressure and slight expansion of kidney, but no diuresis. 



ment and histological features suggest a gland which pours its products 

 into the infundibulum, and so into the ventricles of the brain. It may, 

 therefore, be regarded, in part at least, as a special brain gland. 



Extracts of the anterior lobe have no immediate physiological action 

 when injected into the blood-vessels. 



Extracts of the posterior lobe of birds and bony fishes have an action 

 similar to extracts of the mammalian posterior lobe, bringing about a rise 

 of blood-pressure, expansion of the kidney, and an increase in the secretion 

 of urine. The tissue in which the active principles giving this result are 

 found, contains, when examined histologically, bodies of a colloid nature 

 such as have already been described in mammals in a previous paper. 

 Whether this colloid contains the above-mentioned active principles or not, 

 is undecided ; it may possibly be the expression of some other function. 

 The close relationship which exists between pars nervosa and pars inter- 

 media of the posterior lobe renders it probable that the active principles, 



