OF LIVING FORMS; OR, MORPHOLOGY. 87 



membrane is growing under limit, and is expanding 

 in length while its ends are fixed ? 



If we should ask this question, there are facts 

 which will enable us to answer it. The layer of 

 cells is growing under limit; it is contained in a 

 dense capsule or external membrane, which does 



interfere with its free expansion. There is proof 



* 



Fig. 14. 



Germinal membrane, at early stage (after Bischoff ) ; the cells rounded. 



that this is the case. Fig. 14 represents the cells of 

 which the germinal membrane consists when it is 

 first formed. They are nearly round, and lie in 

 simple contact with each other. But after a short 

 time, as they grow, their shape changes. They 

 become pressed together by the resisting capsule, 



