452 Causes and Course of Organic Evolution 



In some nenierteans Burger describes a connective tissue 

 (Bundegewebe, p. 87) that forms an enclosing box to the brain 

 masses. If we may judge from its structural appearance and 

 staining capacity it seems to be related to cartilage. Further 

 histological and microchemical study might well be made of 

 this tissue. 



The possible relation of the Cyclostomata, the Batrachia, 

 and the Mammaha to each other will next be considered. 



