1923.) Liver and Kidney in Clarias and Saccobranchus. 117 
transverse sections of the isthmus with portions of the extra- 
and intra-coelomic liver attached to both ends shows that the 
coelomic liver and passes through the isthmus, runs upwards 
being imbedded in the dorsal wall of the lobes of the intra-coelo- 
mic liver. It finally leaves the liver at the back of the organ and 
opens into the heart. The hepatic artery, slender in size, enters 
the liver at the union of the right and left halves of the liver. 
The endothelium of the blood vessel is represented by very 
definite and conspicuous cells which are cubical in shape and in 
several instances are seen detached from the underlying mus 
cular fibres. There is a great development of the muscular and 
elastic tissue both in the artery and the vein and specially in the 
smaller blood vessels. 
2. Tyr Kipney.—The entire absence of any uriniferous 
tubules, Malpighian capsules and glomeruli, is the most 
remarkable feature in the histology of extra-coelomic kidney, 
i.e, the lobe lying outside the body wall just underneath the 
skin (Fig. 11). Microscopic examination of transverse sections 
protoplasm is extremely pigmented, and these evidently impart 
the characteristic dark brown colour to the organ. 
never performs any active part in the adult excretory system. 
, erate structure it 
short isthmus. All these facts tend to show that it is a portion 
of the mesonephros which has become degenerated at a later 
Stage of development. . 
n examination of a series of transverse sections of the 
isthmus of the kidney shows that the vriniferous tubules and 
the associated structures gradually disappear as we proceed 
