9 8 



THE TISSUES. 



development and differentiation of the syncytium has been described 

 in full by F. P. Mall, whose account is here followed. As soon as 

 the syncytium is formed its protoplasm grows rapidly, and appears 

 in large bands with spaces between them, and with relatively few 

 nuclei. In its further development the protoplasm of the syncytium 

 differentiates into a fibrillar part, which forms the main portion of 

 the syncytium the exoplasm and a granular part which surrounds 



Fig. 61. Schematic diagram given to show the development of the different types 

 of connective tissue from the mesenchyma : a, Mesenchymal cells, certain of which are 

 separate, others are joined by protoplasmic branches; b, syncytium with large strands of 

 protoplasm and relatively few nuclei ; c, reticular tissue, the dark fibers are elastic fibers ; 

 d, white fibrous tissue ; e, cartilage; f, membranous bone. 



the nucleus the endoplasm. The fibrils of the exoplasm are very 

 delicate and anastomose freely. Probably in all the members of the 

 connective-tissue group, the so-called intercellular substance 

 fibers, matrix of cartilage and bone is developed in or from the 

 exoplasm, while the cellular elements are differentiated from the 

 nuclei and endoplasm. The main features of the development of 

 the different types of connective tissue are portrayed, in part schemati- 



