THE PITUITARY BODY 



a dilute (0.25-0.50 per cent) solution of acetic acid; the mix- 

 ture is quickly brought to boiling and filtered. The water- 

 clear extract can then be stored in ampoules and sterilized 

 by a fractional method. Usually, but not always, such ex- 

 tracts contain about the same proportions of oxytocic and 

 vasopressor principles. This and other evidence have con- 

 vinced some investigators like Abel that only one hormone 

 existed originally and that the oxytocic and vasopressor 

 principles are derived from a single substance. However, un- 

 til this single complete substance has been isolated in pure 

 form, it is simpler to conclude that separate oxytocic and 

 pressor principles exist in the pars neuralis. 



According to Herring (1913), the pituitary of the cyclo- 

 stome {Petromyzon fluviatilis) contains little or no vaso- 

 pressor principle. This is also true of the pituitary of an 

 elasmobranch fish {Raja batis^ or skate); the pituitary of this 

 fish, however, was found to cause a "secretion" of milk in 

 the lactating cat as well as a contraction of the isolated rat's 

 uterus (Herring, 191 5). In the teleost fish {Gadus morrhua, 

 cod) the pituitary but not the saccus vasculosus contains the 

 pressor principle (Herring, 1908). The active principles char- 

 acteristic of the mammalian pars neuralis are found in the 

 pituitary body of amphibia, reptiles, and birds. 



Nearly all the pressor and oxytocic substances in the 

 pituitary of the fowl are found in the pars neuralis (De 

 Lawder, Tarr, and Gelling, 1934). In the ox-pituitary the 

 different anatomical divisions can be rather easily separated. 

 The pars neuralis contains the highest concentration of 

 oxytocic and pressor (including antidiuretic) principles; all 

 the other divisions, except the pars intermedia, contain only 

 very low concentrations of the hormones (Herring, 191 5; 

 Hogben and De Beer, 1925; van Dyke, 1926; and Kurose, 

 1929). Herring as well as Hogben and De Beer concluded 

 that the pars intermedia contained relatively more oxytocic 

 than pressor principle. However, Herring's estimate of the 



[320] 



