PARS NEURALIS AND INTERNAL SECRETION 



because he did not recognize the possibiHty that cerebrospi- 

 nal fluid may contain a pressor substance which is not identi- 

 cal with that of the pars neuralis (Page, 1935 and later). 

 (The pressor substance described by Page is without effect 

 after the complete destruction of the central nervous sys- 

 tem.) Therefore, there remains from Deleonardi's observa- 

 tions the suggestion that cerebrospinal fluid may produce in 

 rats, in a dose of i cc. per hundred gm., a slight diuresis- 

 inhibiting effect similar to that following minute doses of 

 pars neuralis extract. Levitt's observations (1936) must be 

 added to those of others who, contrary to Anselmino and 

 Hoffmann, have been unable to detect the diuresis-inhibiting 

 (vasopressor) hormone in the blood of patients with hyper- 

 tension or eclampsia. Simon (1937), using Marx's method, 

 was unable to extract detectable quantities of vasopressor 

 hormone from 100-200 cc. of human or canine blood (see 

 also Neubach, 1937). The oxytocic effects of blood-extracts 

 (women in second stage of labor, the pregnant cow, the rab- 

 bit before and after injection of pars neuralis extract) have 

 been further investigated by Bell and Robson (1935). They 

 concluded that the oxytocic effects of such extracts, if pres- 

 ent, probably were neither caused by the oxytocic prin- 

 ciple of the pars neuralis nor related to parturition. 



Fisher and Ingram (1936) have shown that the atrophic 

 pars neuralis of cats with diabetes insipidus due to a suffi- 

 ciently extensive lesion of the supraoptico-hypophysial sys- 

 tem contains only one-tenth or less of the normal total 

 amount of the principal hormones of the pars neuralis. The 

 concentration of active principles in the pars neuralis cannot 

 be calculated from their data. The results of Fisher and 

 Ingram are given in Table 9. 



Jores (1935) reported that, if guinea pigs are kept in dark- 

 ness for about 6 hours, the concentration of oxytocic and 

 vasopressor principles in their pituitary bodies increases 

 markedly. This observation was not confirmed by Simon 

 (1936), who used guinea pigs, rabbits, and rats for his ex- 



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