THE DUCTLESS GLANDS 313 



round nucleus whose chromatin forms a peculiar pattern. These cells 

 form various cords, groups, or even acini (Fig. 281). In some of 

 them the cells appear to be surrounding a small lumen that contains a 

 colloid substance like the thyroid substances. Besides these principal 

 cells there is another kind of much the same character, but containing 

 a smaller and deeper staining nucleus. This stains in acid dyes best, and 

 the cells are known as the acidophile cells. 



The blood supply of this tissue is very rich. It consists of an arterial 

 system which percolates through the tissue in large, thin-walled vessels 

 which empty into veins to return to the central, circulatory organ. Be- 

 tween these blood vessels and the gland cells are found but few strands 

 of connective tissue. The vessels are lined by a single, thin endothelial 

 layer. 



Two important secretory tissues are found, in the vertebrate body, 

 which pass their secretion into the blood, where it is of importance to the 

 organism's economy. Their constant presence in the neighborhood of 

 the kidneys has given them the general designation of renal bodies. 



One of these bodies is composed of cells that originated by a devel- 

 opment from cells that otherwise would seem destined to become sym- 

 pathetic nerve cells. Instead of acquiring nerve processes and neuro- 

 fibrils as well as perceptoryand motor end-organs, they acquire a secretory 

 power and (to the eye) a peculiar texture which can best be noticed by 

 placing them in chromium salts, which they take up more readily than 

 other cells, and which stains them a dark brown. 



The secretory power results in the production of an organic substance 

 called "adrenaline," which, when injected into the circulation of the same 

 or other vertebrate animals, causes a contraction of the blood vessels 

 and a consequent rise in blood pressure. These cells are most commonly 

 called the chromaffine cells, and they form the paraganglionic bodies, 

 as this sort of tissue has been called. Chromaffine cells may be devel- 

 oped in other situations than in the renal bodies, and perhaps from other 

 cells than young nerve cells. The function of such cells would appear 

 to be the same. Many isolated chromaffine cells also appear in other- 

 wise purely nervous, sympathetic ganglia. 



The second sort of tissue which takes part in forming some renal 

 bodies is not so well known, and we shall use the name by which it has 

 been most known, the cortical tissue of the renal bodies. 



This tissue is composed, as a rule, of smaller cells arranged in cords 

 which lie between a series of anastomosing blood vessels. The cells 

 lie side by side in the cords, and form approximately rows which resem- 

 ble true glands without a lumen. They probably secrete some substance 

 into the blood. 



These cortex cells are derived from some of the surrounding meso- 



