SYSTEMATIC SYNTHESIS OF TISSUES. 



191 



Remark. One of the most important lessons to be learned from a 

 review of all the tissues is, that Time is one of the essential elements in 

 their production, and it will be found that the more Time the plant has 

 for perfecting its compounds the better, and that a perfect work cannot 

 be done by the animal tissues without Time is allowed for their compo- 

 sition. The Brain, in particular, requires time for its perfection, and 

 if it is made active too long, or with too brief intervals of repose, its 

 cells do not become mature and perfect, and nervous excitement, irrita- 

 bility, and other disorders will be manifested or ensue. The constant 

 activity of city life requires long periods of repose. Students should 

 sleep much and well ; and for recuperation of any part, repose, rest, 

 and quiet, are necessary. 



SECTION VIII. 



Compound Tissues. 



198; ADIPOSE TISSUE is usually treated as if it were 

 a distinct Tissue, but it is merely cells, the walls of which 



FIG. 154. 



FIG. 155. 



Fig. 154 represents a cluster of fat cells inclosed in a 

 small number of sinewy fibres, as if entangled in a net. 



Fig. 155 represents, at 1, a very highly magnified view 

 of capillary blood-vessels woven around and among the 

 fat cells ; 2 is three cells with loops of vessels around them; 

 5, a compressed cluster of cells ; 3, an artery ; 4, a vein. 



What said of time? Why does repair of brain require time ? 198. What ? 

 Describe Fig. 154. Describe Fig. 155. 



