clxxxii Journal of the Asiatic Society of BemjaL [N.S., XIII, 



i aused a flow of arterial blood and oxygenated saline to traverse the 

 venous channels of the kidney : urine was produced abundantly while the 

 renal arteries were intact, but on ligaturing these the secretion entirely 

 ceased. 



The conclusions to be drawn from all the above experiments (to be 

 published in full in due course) are (1) that toads and frogs can live with 

 their kidneys solely supplied by the renal arteries* the venous supply to the 

 kidneys being unessential ; (2) that although the venous supply to the 

 kidney maintains blood pressure in that organ , yet since this function 

 can readily be taken on by the penetration of the arterial blood into the 

 venous sinuses of the kidney, it is not an essential feature of the venous 

 supply ; (3) that experimental facts prove that the arterial capillaries 

 of the kidney open into the venous sinuses of the renal venous meshwork 

 ('* renal portal system ") after the former have supplied both the Malpighian 

 capsules and the tubules , and that therefore the venous blood does not come 

 into contact with the excretory cells in a functional capacity, i.e. the venous 

 blood never penetrates under normal conditions into the arterial inter- 

 tubular plexus or the glomeruli ; (4) that the fact that in my perfusion 

 experiments the urine of the arterial kidney was more dilute (in nitrogen- 

 ous contents ) than the urine of the normal kidney (i.e. with a venous 

 supply) is to be accounted for by the further facts that in the normal 

 kidney of these experiments the venous blood supply contained more 

 diuretic in solution (due to addition of waste products from the leg 

 tissues) than the arterial blood (diluted by perfusion saline introduced 

 into renal arteries) and therefore diuretic diffused from the venous 

 sinuses in the kidney into the arterial intertubular capillaries, thus 

 making the arterial blood in these capillaries strong in diuretic ; in the 

 arterial kidney this venous supply was absent and the arterial blood con- 

 sequently weaker. Since under normal conditions the arterial blood con- 

 tains as much waste nitrogenous matter in solution as the venous, no such 

 diffusion would occur, and the urine produced by an arterial kidney is as 

 strong as that produced by a normal kidney (as proved by the non-perfu- 

 sion experiments quoted above and by the experiments* of Bainbridze, 

 Collins and Menzies). Evidence from all sources therefore proves that 

 the renal venous meshwork (" renal portal" system) is, under normal 

 conditions, devoid of junction. 



A revision of the Indian Species of Meretrix. — By J. Horneix 



The genus Meretrix contains a number of estuarine species. Those 

 living in the waters of Continental India are exceedingly variable in re- 

 gard to colouring, shape, or both combined. Ignorance of this fact has 

 led to great taxonomic confusion and to the undue multiplication of 

 species. There are really only two good species living on the Indian 

 mainland, viz. M. meretrix and M. casta. The former is very variable 

 in colour, particularly when young, but is stable in size and shape when 

 mature; the latter varies with differing environment, resulting in the 

 production of several varieties and local forms. The forms found in the 

 east coast estuaries of M. casta are true to type within narrow limits ; 

 while those meretrix living on the west coast vary greatly and present 

 several varieties, which, however, are all connected by a perfect series of 

 intermediate variations. The author gives a key to the Indian Species 



arm varieties nf lf»of»a/>. J 



and varieties of Meretrix. 



A new Protozoan cause of widespread Mortality among Marine 



Fishes.— By J. Horneli 



Several theories have been advanced to explain the annually recurring 

 tality among fishes and crabs on the Malabar and S. Canara Coasts. 



.i U .»i.v, ..iuuHg nsnes ana crabs on the Malabar and S. Canara coas^- 

 Among these may be specially mentioned (1) Suffocation by excessive 



