94 



THE ESSENTIALS OF HISTOLOGY 



different parts, which is mainly determined by the disposition of the 

 tissue-elements, may best be studied when the structure of the several 

 organs is considered. 



In the transparent parts of animals, the blood may be seen flowing 

 through the capillary network from the arteries into the veins. Tne 



FlG. 117. A SMALL ARTERY, A, AND VEIN, V, FROM THE SUBCUTANEOUS CONNECTIVE 

 TISSUE OF THE RAT, TREATED WITH NITRATE OF SILVER. (175 diameters.) 



a, a, epitheloid cells with b, b, their nuclei ; m, m, transverse markings due to staining of 

 substance between the muscular fibre-cells; c, c, nuclei of connective-tissue corpuscles 

 attached to exterior of vessel. 



current is very rapid in the small arteries, somewhat less so in the 

 veins, and comparatively slow in the capillaries. The current is fastest 

 in the centre of the vessel, slowest near the wall (inert layer), and 

 with care it may be observed especially where there is any commen- 

 cing inflammation of the part, as in the mesentery in consequence of 



