138 THE MICROSCOPIST. 



6. Simple isolated cells, forming solid tissues by their 

 aggregation ; as fat cells, the vesicles of gray nervous matter, 

 absorbed cells of the villi, and the cellular parenchyma of the 

 spleen. In these cases the cells are held together by the blood- 

 vessels and areolar tissue, which pass in between them ; in car- 

 tilage, and other tissues allied to it in structure, the cells are 

 united by intercellular substance, either homogeneous, or of a 

 fibrous character. 



7. Sclerous or hard tissues, in which the cells have been 

 more or less consolidated by internal deposit, and more or less 

 completely coalesced with each other; as the hair, nails, &c. 

 These instances may be more properly ranked under the epi- 

 dermic tissues ; the result of consolidated deposit is more cha- 

 racteristically seen in bones and teeth. 



8. Tubular tissues ; formed by the coalescence of the cavi- 

 ties of cells ; as in the capillary blood-vessels, muscular fibre, 

 tubuli of nerves, &c. 



In some of these, as muscle and nerve, a deposit has taken 

 place subsequently to the coalescence of the original cells. 



To these we may add, 9. Compound tissue; formed of 

 areolar tissue and cartilage ; as fibro-cartilage. 



