98 MANUAL OF HISTOLOGY. 



61. 



As we have just seen, the intercellular matter between the formative 

 cells of the capillaries appears in the most minute quantity, reminding us 

 of the allied tissue epithelium (fig. 81). 



But it is otherwise in certain textures which, though appearing under 

 great variety of changeable forms, are yet connected by intermediate links, 

 and merge at times from one variety into another. These must be regarded, 

 consequently, as members of one natural group, and are known as the con- 

 nective substances. Cartilage, the consideration of which occupied us in 

 a former section ( 53), is one of these ; further, colloid, reticular, and 

 ordinary connective tissue, fatty, bony, and nearly related to the latter 

 dentine tissue, must be also reckoned as belonging to them. 



In all those various forms in which the members of this widely-spread 

 group of connective substances appear, we meet with cells imbedded 



in more or less abundant intercellu- 

 lar substance. The cells, however, 

 display very different characters in 

 different instances, and no less so 

 the intercellular substance, which 

 may be found either in the form 

 of mucoid jelly, fibrous, and more 

 solid substance, or of hard stony 



Fig. 101. Tissue of the vitreous humor of a hu- matter 



The' vitreous humor of the foetal 



eye affords a beautiful example of an extremely simple texture (fig. 101). 

 Simple nucleated cells lie here in a watery jelly. If we can imagine 

 the latter replaced by a solid mass of chrondin, we have the well-known 

 appearance of cartilage (fig. 83). 



It is seldom, however, that in the group of tissues under consideration 

 the cells remain in an abundant intercellular substance, so slightly 

 matured, as in cartilage. Crowded together, they may perhaps increase 

 in size, and, retaining their spherical shape, become rilled with neutral 

 fats, as is the case with fat-cells which have this origin, 

 as far as is known at present. But, as a rule, the forma- 

 tive cells of the connective-tissue group abandon the 

 spheroidal form, and grow irregularly. 



At one time they become fusiform by extension in 

 Fipr. 102. stellate ceils two opposite directions, as we have seen in a similar 

 suc - case, though on a far larger scale, among the elements 

 of involuntary muscle (comp. tig. 96, p. 95) ; at another they assume 

 more or less of a stellate form (fig. 102). 



And, just as certain connective-tissue cells may become fat-cells, so at 

 this stage of development many pigments may be laid down in their 

 bodies, terminating their transformations. It is in this way that the 

 structures known as stellate pigment-cells are formed (fig. 50, p. 68). 



In their further progress in development, connective-tissue cells mani- 

 fest, besides a tendency to continuous elongation, an inclination to fuse 

 with one another. In this way, by the cohesion of the processes of 

 adjoining cells, extremely delicate cellular networks are formed (fig. 103), 

 whose meshes are occupied by a mucoid jelly. But this latter may again 

 disappear, and be replaced by totally different matters, as, for instance, by 

 lymph-corpuscles. As they grow older, also, connective-tissue cells, tense 

 and full when young, may shrink and decrease very considerably in volume. 

 But, as already mentioned, the variety which the intercellular substance 



