§ 5 HAEMO- AND NEUROCRINIA OF HYPOPHYSIS 69 



having thickened parts, and generally closely connected with 

 similar cells. It is not known whether these are genuine des- 

 cendants from ganglion cells forming an intramural nervous 

 system, or glia-derivatives, and up to the present their signi- 

 ficance is not clear. It is interesting that the lobus anterior, 

 the seat of the gonadotropic cells, is in direct nervous con- 

 nexion with the principal tracts coming from the hypotha- 

 lamus. It would seem reasonable, therefore, to assume the 

 existence of a nervous regulation of the hypophysis in fishes. 



§ 5. THE HAEMO- AND NEUROCRINIA OF THE HYPOPHYSIS 

 OF THE BITTERLING 



Bretschneider (vide p. 49) has shown that the acidophil 

 stage constitutes the phase of formation of the gonadotropic 

 secretions and the basophil stage the phase of their liberation. 

 He was the first to discover this in the bitterling. In an 

 endeavour to find out more about the activity of the hypo- 

 physis we have studied the haemocrine secretion of the lobus 

 anterior and the neurocrine secretion of the lobus intermedius. 

 Whereas BRETSCHNEIDER examined the activity of the lobus 

 anterior during the action of steroid hormones, VAN lERSEL 

 was able to follow this activity under natural conditions and 

 during the whole of the annual cycle, as well as during 

 oviposition, by measuring the sum of all basophil cell islands 

 in the entire gonadotrophic zone (either planimetrically or by 

 means of a photo-electric cell), and calculating the percentage 

 of the total superficial area of the lobus anterior which they 

 occupy. Bretschneider found, for four steroid hormones 

 examined, secretion of gonadotrophic hormones, which fluc- 

 tuated between 15 minutes with progesterone and 2 hours 

 with luteidin (a substance found by means of the ovipositor 

 test, in human urine; vide p. 34) followed by a restitution 

 period of varying duration. The action of these haemocrine 

 gonadotrophic hormones may be measured by the degree of 

 luteinisation in the ovary, and by their effect on the ovi- 

 positor. The rate of secretion was slower under natural con- 

 ditions during oviposition. VAN lERSEL found it to be slow 



