138 



TEXT-BOOK OF EMBRYOLOGY. 



Ectoplasm with 

 "white" fibers 



Ground 

 substance 



Ectoplasm 



FiG. 112.- Connective tissue cells from intervertebral disk of calf embryo; showing origin of 

 "white" and elastic fibers in protoplasm of cells. Ectoplasm represents a modified part 

 of the protoplasm. Hansen. 



Osteogenetio 

 tissue 



FIG. 113. Vertical section through frontal bone of human foetus of 4 months. 

 (Intramembranous ossification.) Photograph. 



