BLOOD-VASCULAR SYSTEM, ETC., OF AMIURUS CATUS. 439 



11, B). Tliey stain deeply and evenly throughout like the nuclei of 

 the blood cells or the nucleoli of the ordinary suprarenal cells, but 

 are larger and more irregular in form. They are most probably small 

 ganglion cells. 



The blood-vessels of the bodies are small and the capillaries do not 

 seem to be abundant, which explains their pale color. The blood 

 supply seems no more than sufficient for the nourishment of func- 

 tionally active organs of their size.* Mr. Weldon 1 lately suggested 

 that these bodies are probably related to the kidney and perform 

 some function in connection with the elaboration of the blood. 

 My observations upon Amiurus, although imperfect, are opposed to 

 such conclusions. The smallness of the blood supply, the absence 

 of ducts and of all stored up remains of its action, such as the 

 brown pigment of the kidney, head-kidney and spleen, or the colloid 

 matter of the thyroid, and also its structure, mark it off from the 

 other blood-glands. He further remarks : " In Teleostei supra- 

 renals are at all events frequently absent ; or, as I would rather 

 suggest, they are represented by the greatly metamorphosed head- 

 kidney described by Balfour. In other cases whex-e suprarenals have 

 been detected, they have always been attached to the surface of 

 the kidney." In regard to the first point, we have in the cat-fish a 

 well developed head- kidney in which the metamorphosis can be 

 traced and which preserves its relation to the renal-portal system, 

 and presents the characteristics of a blood-gland. The position upon 

 the surface of the kidney is no doubt due to the development of the 

 latter causing it to press upon the body and carry it outward upon 

 its surface. It is certainly neither connected with the kidney nor 

 yet with its blood-vascular system in the adult, whatever may be its 

 developmental relationships. 



Certain, other gland-like structures are attached to the walls of the 

 veins in the body cavity. They were observed in sections of the 

 head -kidney surrounding the cardinal vein, but are specially abundant 

 on the portal vein between the spleen and the liver. They are 

 small white bodies varying in size and form, sometimes appearing 

 small and rounded upon the side of the vessel, sometimes forming a 



* Note. — In teased preparations the blood cells bear a very small proportion to the other cellg. 

 1 Quart. Jour. Mic. Sc, N. S., Vol. XXIV., p. 176. 



