402 THE PINEAL ORGAN 





# 





•f 









4 



*► ¥ 



A B 



Fig. 271. — A— Pineal Gland of a Newly Born Lamb. B— Pineal Gland of 

 a Sheep aged 4 years. (After R. Amprino.) 



glial syncytium ; glial fibres ; and the tortuous thick fibrils which have 

 been specially described and figured by Amprino (1935) (Figs. 269, 270, 

 271, 272). 



An intercellular substance is difficult to demonstrate with certainty, 

 and possibly in the living subject simply exists as an albuminous semi-fluid 

 material which everywhere fills the intercellular spaces. It is also probable 

 that in the preparation of specimens for microscopic examination the 

 coagulable material present in the interstitial tissue-fluid is concentrated 

 on the cellular elements and fibres, so as to form on these a continuous 

 membrane-like covering, such as was described by Held as the " grenz 

 membran." On the other hand, it is quite possible that a similar process 

 may occur normally during life and a more solid constituent be separated 

 out from the more liquid intercellular tissue-fluid, the more solid material 

 being deposited on the surface of the cellular elements and fibres and 

 thus forming a continuous membrane-like covering or, when it completely 

 fills the spaces, an intercellular ground substance. Such a conception is 

 important in connection with the passage of nutritive material, or possibly 

 secretory products, into or out of the cell-bodies and their processes — 



