vi HISTOLOGY OF THE FROG 125 



inelastic, and mainly composed of fibers, all of which lie in 

 one direction. The loose tissue of lymphatic glands belongs 

 to a variety called adenoid, which is composed of an irregular 

 network of sheets and strands forming a fine meshwork which 

 supports the cells. The ligaments uniting the bones together 

 are formed of a very dense and inelastic variety of white 

 fibrous tissue. Modifications of the same kind of tissue 

 occur in the cutis of the skin, in the submucosa of the 

 alimentary canal, in the substance of glands and the capsules 

 surrounding various organs. 



Adipose tissue may be regarded as a form of connective 

 tissue in which many of the cells have become enlarged 

 through being gorged with fat ; the nucleus with a small 

 amount of protoplasm lies to one side of the cell, and the 

 cell wall and a thin pellicle of protoplasm surround the 

 globule of fat. In its early stages the fat cell may contain 

 several isolated droplets of oily substance which as they grow 

 coalesce into a single large mass. 



Cartilage is a dense massive variety of connective tissue. 

 In the clear hyaline cartilage which is the predominant variety 

 in the frog, the matrix appears transparent and homogene- 

 ous, although under proper treatment it may be shown to 

 contain numerous fibers which ordinarily are not evident. 

 The cells are contained in rounded spaces or lacunae, scat- 

 tered irregularly through the matrix; in some cases minute 

 channels have been observed connecting the neighboring 

 lacunae together. Two or more cells are often found in one 

 lacuna, a fact which indicates that they have recently arisen 

 by the division of the parent cell. Each cell causes the 

 deposit around it of intercellular substance ; and the cells 

 separated by cleavage soon form a partition between each 

 other which gradually increases in thickness and presses the 

 cells farther and farther apart. The outer surfaces of car- 



