§ 6 



SUMMARY 



73 



lobus. ant. lob. int. 



lob. ant. lob. 

 + Rhodeus amarus 



'nt 



Fig. 58. The pituitary in Rhodeus amarus $ and $ . 



Our experiments show that the haemocrine secretion occurs in 

 the lobus anterior all the year round, while the colloid secre- 

 tion from this lobe is added to it only in spring, or very 

 sporadically in winter. There is no doubt that this neurocrine 

 secretion of hormones near the brain has some connexion 

 with a nerve centre in the central nervous system. We are 

 inclined to think that the lobus intermedius is connected with 

 the chromatophores, and we know that, in teleostean fishes, 

 the chromatophores are regulated both nervously and hor- 

 monally. Since colour pattern and adaptation to surroundings 

 play an important part in the life of fishes, the marked 

 development of this lobe may thereby be explained. Such an 

 explanation is also indicated by the fact that in the male 

 bitterling, where nuptial characters are well-developed, the 

 lobus intermedius is larger than in the female whereas in the 

 latter the lobus anterior, with its extensive gonadotrophic 

 zone, is more strongly developed than in the male (Fig. 58). 



Summary (Figs. 59 and 60). 



I. The simple construction of the hypophysis of the bit- 

 terling makes it a suitable object of study for the quantitative 

 and qualitative determination of the formation and secretion 

 of the gonadotrophic hormone as a result of exogenous 

 stimuli. 



