STRUCTURE OF THE PINEAL ORGAN OF REPTILES 251 



represent secretory threads, cilia, or protoplasmic processes of the cells, 

 similar to those present in the pineal eye of Geotria or Petromyzon. 



Ep. 



lob — ~l_ y^°° 

 caps. — 



Fig. 179. 



A — The epiphysis of a young embryo of a water snake, Tropidonotus. The 

 ependymal tissue is penetrated by ingrowing septa of connective tissue, 

 containing capillary blood-vessels, and is subdivided into rounded lobules. 



B — The epiphysis of an older specimen of Tropidonotus ; the organ now appears 

 as a solid mass of tissue ; all traces of lobulation and plexus of capillary 

 vessels having disappeared ; degeneration being indicated by the formation 

 of spaces which are not lined by endothelium. (After Leydig.) 



