TISSUES, ORGANS, AND SYSTEMS. 7!) 



entirely consists of it. Virchow believed that it ought to be 

 distinguished from connective tissue, and proposed the denomi- 

 nation of mucous tissue (tissu muqueux) for it. I considered 

 it from the first to be connective tissue, and I now feel 

 the more inclined to remain of this opinion, because I find 

 that every description of the areolated connective tissue of em- 

 bryos originally commences under this form, and therefore 

 the circumstance that the tissue in the umbilical cord never 

 arrives at perfection, cannot determine its nature. 



The mode in which the gelatimform connective tissue is deve- 

 loped is this : one portion of the cells contained in the gelati- 

 nous basis changes into connective tissue by becoming fusiform, 

 and breaking up into common or reticulated, anastomosing 

 connective tissue, which however, as Schwann has already 

 stated, at first yields no gelatine. In this manner a closer or 

 denser network arises, in the interspaces of which the inter- 

 mediate substance or matrix, and a remainder of the previous 

 formative cells, are contained. In the further course of deve- 

 lopment, new cells proceed from the matrix, which hereby 

 diminishes by degrees in quantity, and at the same time the 

 original network consolidates, fresh cells being added to it, a 

 part of which also become elastic fibres and vessels. If subse- 

 quently the areolated connective tissue includes no adipose 

 cells, the gelatinous tissue ends by completely disappearing, 

 and nothing remains but a loose fibrous tissue, containing at 

 most somewhat less fluid, and loose cells in its meshes; if, on 

 the other hand, it becomes converted into an adipose tissue, the 

 spaces remain, and a great part of the cells which have arisen 

 at the expense of the gelatinous substance, subsequently pass, 

 by the development of fat in their interior, into fat-cells. 



In the gelatinous tissue of Wharton, between the chorion 

 and amnion, and in part in the enamel organ, the areolated 

 connective tissue remains more in its fcetal condition of a gela- 

 tinous tissue, yet there exists no natural line of demarcation 

 from ordinary connective tissue, so much the less, since in 

 the gelatinous substance of Wharton, in older embryos 

 even fibrils are quite evident, and in the enamel organ the 

 passage of a part of the gelatinous tissue into common con- 

 nective tissue is demonstrable. 



So much for the two types of development of the connective 



