THE DUCTLESS GLANDS 



317 



must pass slowly through such an enlarged vessel. The cells are thus 

 in an advantageous position from which to receive food materials and 





FIG. 285. Section through a lobule of the coccygeal gland of man. 

 sec.c., secreting cells; bl.v., blood vessel. (After WALKER.) 



oxygen from the blood, to discharge their waste matter into it, and also 

 to give up to it their secretion product, which must be of some use to the 

 body or else the tissue would not exist. This gland is found in the body 

 of man from fcetal life to death, and the one change which marks its 

 greater age is a larger amount of connective tissue which does not exist 

 at first in the cell masses. 



On account of the anatomical position of the gland as well as the 

 structure and physiological 

 reactions of its specific cells, 

 it has been supposed to be 

 an homologue of the inter- 

 renal body of the elasmo- 

 branch fishes. This idea 

 must remain as a mere spec- 

 ulation for the present. 



Another gland of interest 

 is the carotid gland, which is 

 found in man as a small 

 mass of yellowish red tissue 

 placed at the bifurcation of 

 the carotid artery. It is a 

 little larger than a large grain 

 of wheat, and might be com- FlG 286 _ Section of the carotid goi man . secx ., 



pared closely tO the COCCVg- secreting cells surrounded by blood channels. (After 



eal gland as to its structure. SCHAPER.) 



It has much the same kind of secreting cells, and these cells border 



upon a blood space from which they are separated by the very thinnest 



