TISSUES. 67 



known as Wharton's jelly, or mucous tissue. These 

 cells are loosely associated in no definite order, their 

 stellate processes interlace and sometimes appeal 

 to come in direct contact. Their nuclei are round, 

 or oval, or elongated, forming what is known as the 

 spindle-shaped and pointed nucleus, often resem- 

 bling the cigar-shaped and rounded nucleus of a plain 

 muscle cell. The nuclei are rich in chromatin, and 

 therefore stain heavily with hematoxylin. Blood- 

 and lymph- vessels mingle freely with these cells; in 



Fig. 32. Two pigment cells from the dermis of a salamander. The 

 pigment is in the cytoplasm. 



fact, this association is constant. The so-called 

 granulation tissue in healing wounds consists of em- 

 bryonic connective-tissue cells, always bleeds easily, 

 because of its vascularity, and painless because of 

 absence of nerve endings. 



(b) Pigment Cells. These are connective-tissue 

 cells in which pigment is stored in the cytoplasm, 

 never in the nucleus. The cells are extensively 

 branched, large and flat. In amphibians and rep- 

 tiles they are abundant in the dermis of the skin, and 

 enable the animal to change its color, as is the case 

 with the tree toad and the chameleon. In the human 



