THE PITUITARY BODY 



circulated through the head and is then circulated through 

 the isolated kidney may not only inhibit the secretion of the 

 urine but also bring about an increase in the concentration 

 of chloride in the urine. However, if the pituitary body has 

 been removed, the blood causes no similar change in the secre- 

 tion of the urine. Experiments confirming those of Verney 

 have been performed by Compere (1932-33). ^ The con- 

 clusion reached by means of such experiments has appeared 

 to Fee (1929) and to Newton and Smirk (1934) not to be 

 justified. Indeed, Newton and Smirk believed that neither 

 the pituitary body nor the hypothalamus are essential for 

 the control of water diuresis. 



In Dixon's acute experiments (1923), various procedures 

 caused marked changes in the apparent concentration of 

 oxytocic hormone in the cerebrospinal fluid of dogs. How- 

 ever, he was unable to explain his observation that no dimi- 

 nution occurred after hypophysectomy. 



Can the active principles of the pars neuralis be recognized 

 in the cerebrospinal fluid and blood of normal or diseased ani- 

 mals? I. The oxytocic principle. — The concentrations of the 

 "hormones" of the pars neuralis in the cerebrospinal fluid (in 

 most experiments, the oxytocic principle has been investi- 

 gated) vary remarkedly in the different reports. A "normal" 

 variation of 300-2,000 per cent has been found by several 

 authors who investigated cerebrospinal fluid or blood. In 

 normal mammals estimates of the concentration of oxytocic 

 substance in cerebrospinal fluid have differed by as much as 

 five thousand times (500,000 per cent)! If the true active 

 principles were really being determined, it would be a remark- 

 able biological fact that the concentration of such powerful 

 substances could vary so greatly. One is, therefore, driven 

 to accept one (or more) of the following conclusions: {a) the 

 assays are not specific for the true active principles so that 

 the true concentration, if any, is not known; or {b) only a few 



7 See also Klisiecki, Pickford, Rothschild, and Verney (1933). 



[ ZT~ ] 



