§ 6 SUMMARY 75 



the vertebrate pituitary. The basic plan of the hypophysis of 

 Sauropsida and mammals (Gallus, Felis) may be inferred 

 from the turning of the hypophysis axis (Carpiodes and 

 Zoarces) and a certain independence of the lobus tuberalis 

 (Xenopus and Bufo). The term "Uebergangsteil" (transit- 

 ory part) should be dropped, and replaced by the term lobus 

 anterior. It appears from the position of the gonadotrophic 

 glandular cells, described on p. 56, that, in fishes, these are 

 present also in the lobus anterior, and that, therefore, the 

 hypophysis in fishes does not deviate from the structural plan 

 as known at present. 



3. From an investigation of the blood supply, the inner- 

 vation, and the haemo- and neurocrinia of the hypophysis of 

 the bitterling we are now able to form the following pro- 

 visional picture (Fig. 60A). 



a. There is a connexion between the periphery (i.e., the 

 outside world) and the hypophysis, through tracts running 

 from the senses to the hypothalamus and thence to the hypo- 

 physis. Here, the glandular cells are stimulated to produce 

 their hormone which passes to the effector (the ovary) via 

 the blood. 



6. When steroid hormones are added to the aquarium 

 water, the stimulus passes through the blood vessels of the 

 gills and probably reaches a centre in the brain, whence a 

 nervous stimulus then acts on the glandular cells in the hypo- 

 physis. These glandular cells send their hormones through 

 the blood to the effector, the ovary. The stimulus described 

 on p. 26, from the ovary to the hypophysis, will also be 

 received in the brain, reaching the hypophysis via nervous 

 channels (Fig. 60B). In both cases, therefore, there is a 

 nervous path to the hypophysis, and a blood path to the 

 effector. As is evident from experiments and the observation 

 of the normal course of events during the year, secretion into 

 the blood is completed rapidly, taking not more than one 

 day. 



c. By a third channel (Fig. 60C) the hypophysis receives 

 from the brain a nervous stimulus, after which the glandular 



