PARS NEURALIS AND INTERNAL SECRETION 



conclusion was based upon experiments in dogs with intact 

 pituitaries. Presumably more vasopressor hormone was se- 

 creted as the water load diminished. 



By means of acute experiments in rabbits which had re- 

 ceived neither food nor water for 24-48 hours, Janssen (1935) 

 found that afferent stimuli could cause an increased rate of 

 secretion of urine in which the concentration of chloride rose. 

 The fact that this effect occurred after renal denervation led 

 to the conclusion that it was due to the reflex secretion of a 

 hormone. Theobald and Verney (1935) measured the action 

 of afferent stimuli" on the secretion of urine by the denerv- 

 ated kidney of the dog in which diuresis was provoked by 

 water. Inhibition of diuresis was readily produced and some- 

 times persisted for 5-20 minutes after the removal of the 

 stimulating agent. The authors concluded that the diuresis 

 inhibition was not caused by epinephrine and suggested that 

 the hormone responsible for the effect was secreted by the 

 pars neuralis. This suggestion seems logical and is in agree- 

 ment with both the earlier work of Verney and his colleagues 

 and with nearly all recent observations. 



Brull (1937) concluded that an unknown pituitary prin- 

 ciple (not those recognized in the pars neuralis and neither 

 gonadotropic nor thyrotropic hormone) can lower the thresh- 

 old of renal excretion of inorganic phosphate, provided that 

 the parathyroid hormone is also present. 



The vasopressor principle. B. As a regulator of the cardio- 

 vascular system. — Blount (1935) transplanted two pituitary 

 anlagen (including the future pars neuralis) into individual 

 urodele larvae, Amblystoma punctatum., and concluded that 

 the symptoms appearing later were analogous to hyperten- 

 sion in man. He based this conclusion particularly on the 

 reduction in the size and number of the peripheral capillaries 

 associated with "labored attempt(s) at propulsion of cor- 

 puscles" and an "increased back-flux of diastole." The heart 



" E.g., by the insertion of a hypodermic needle in the region of the fourth lumbar 

 interspace. 



[2851 



