70 



HYPOPHYSIS— yOVARY->-OVIPOSITOR 



II 



<S Qmonths 



10 n 12 1 



8 9 10 months 



Fig. 56. The relation between haemocrinia and neurocrinia during the 

 cycle in Rhodeus amarus. 



during the 2 days before oviposition but rising rapidly 

 during that process. There followed an equally rapid res- 

 titution (Fig, 56b). 



a. During oviposition induced by natural stimuli, there 

 is a less protracted secretion than during oviposition induced 

 by hormones from other species. It is still, however, a rela- 

 tively rapid process. This is characteristic both of nervous 

 regulation and of haemocrine secretion. Determination of this 

 haemocrine secretion of the lobus anterior throughout the 

 year shows a steady minimum rate in inter-estrus (from 

 September to February), and a high rate in pro-estrus 

 (March), while during estrus, coinciding with every ovipo- 

 sition, the maximum is reached. After this, secretion falls 

 again rapidly to the inter-estrus rate (Fig. 56c). 



b. The transport of hormones through the lobus posterior. 

 The secretion from the lobus tuberalis passes exclusively into 

 the blood. That from the lobus anterior is only partly 

 absorbed by the blood. The rest, together with the hormone 

 from the lobus intermedius, passes in the form of a "colloid" 

 through the lobus posterior to the brain. The tissue of the 

 lobus posterior consists mainly of glia, forming a system of 

 fibrous structure running from the thalamus, through the 

 stalk into the hypophysis, passing through all branches of 



