§ 5 HAEMO- AND NEUROCRINIA OF HYPOPHYSIS 71 



the lobe and a considerable part of the glandular tissue (Fig. 

 57). Its parallel fibrous construction suggests that the action 

 of the lobus posterior may be compared to that of the wick 

 of a lamp, the incretion being sucked through the stalk to the 

 hypothalamus. The hormone from the lobus intermedius 

 passes in the form of droplets or granules into the lobus 

 posterior. Near the hypophysial stalk the droplets flow 

 together to form larger drops, usually oblong in shape (Fig. 

 57). Van Iersel gave a rough estimate of the amount of 



cross -section Neurocnny 



Fig. 57. Neurocrinia in Rhodeus amarus. 



neurocrinia of the lobus intermedius over a period of twelve 

 months and concluded that in winter the glandular cells 

 contain a maximum amount of incretion, whereas in spring 

 and summer thev contain less (Fig. 56d). This corresponds 

 with the active phase of the lobus intermedius when the cells 

 lose their marked chromophilia and turn a lighter colour, 

 and also with the time when the lobus posterior becomes 

 filled with colloid. This rough calculation indicated that the 

 neurocrine secretion reaches its maximum at estrus and ex- 

 tends over a fairly long period, being more protracted than 

 the haemocrine secretion of the lobus anterior (Fig. 56c). 

 Especially in spring, but sometimes also in our experiments 

 made during the winter, extra colloid formation takes place, 

 for which we have so far failed to find a satisfactory explana- 

 tion. From the fairly regular appearance of this phenomenon 

 in the spring, however, we may assume that there cannot be 

 anything abnormal about its occurrence. In a large part of the 

 acidophil tissue the colloid appears at the cellapex in the form 



