54 



HISTOLOGY. 



tissue fibrils begin to be formed. This gelatinous tissue is found 

 in the umbilical cord, and also in the embryonic cutis. h is 

 not to be considered as a separate kind of tissue, but only ;i> 

 an early stage in the development of the true fibrillar connec- 

 tive tissue. A similar tissue is present in the" vitreous humor of 



FIG. 27. 



\ 



v 





_. I 



Embryonic connective tissue from the subcutaneous layer of the skin of a three and a half 

 day old chick, x 640. Two karyokinetic figures are seen. 



the eye, where, however, the homogeneous semifluid ground 

 substance is very abundant and the cells have in large part 

 disappeared. 



(b) Areolar or Fibrillar Connective Tissue. The intercellular 

 substance contains formed elements of two different kinds: 

 the white connective-tissue fibrils, and the elastic fibres. There 

 are also cells of various kinds present (Fig. 21)). 



(1) Intercellular Substance. (a) The white connective-tissue 

 fibrils consist of collagen i.e., when boiled they yield gelatin 

 (glutin). These fibres run always in bundles (Fig. 30), and when 

 they are present in large quantities are known as white fibrous 



