Consideration from the viewpυint of comparative physiology
In the 1st to 3rd phylum (ameba，s ponge and jellyfish)，wastes are removed by the influx and effux of external water. In the 4th to 7th phylum (liver f1uke，earthworm，lingula jaspidea and crab)，the renal duct appears to clean the fluid in the body cavity. In Octopus vulgaris，stratified basket-like vascular plexuses are noted in the renal capsule，suggesting urine secretion.
In the vertebrata，no glomerulus appear in sea devils but in sharks and carp，glomeruli
appear all over the kidney with distribution of renal arteries and portal veins. In the fowl，glomeruli appear only in the cortex with portal veins distributed in some. In the mammalia，the portal veins disappear. With the evolution of animals，the
number of glomeruli increases poportionately.
Amount of muscles of the renal arterial system
There is active contractility and passive contractility in the contractility of artery. Passive contractility is due to extensibility and tension of the entire wall and active contractility is due to musculaてcells. Therefore，active contractility of a certain portion
may be considered to be in proportion to the number of muscular cells. Tissue sections measuring 10μ were made from various parts of the renal artery to determine the number of muscular cell nuclei and it was found that the number of muscular cell nuclei in the renal artery was larger than that in the cerebral artery but smaller than that in the hepatic or splenic arteries.
Glomerular blood vessels and blood ftow
It has so far been considered that the glomerular efferent blood vessel has strong
contractility which adjusts blood pressure within the glomerulus. However，muscular
cells exist in greater number in the afferent blood vessel and contract strongly by adrenalin. As to glomerular blood flow，some hold that blood flow stops at the time of rest and others take the view that it does not. This discrepancy is due to difference in the method of experiment. In light of experiments made with due consideration of the method，and clarification of the mechanism by which glomerular blood flow is adjusted，it will be more physiological to consider that glomerular blood flow at the time of rest is not constant.
Distribution of vasomotor nerves to the renal blood vessel
As to distribution of vasomotor nervcs to the kidney，distribution of vagus nerve
and sympathetic nerve can be considerered. Especially as to the vasodilator nerve，there are many points yet to be clarified， so experiment was made on Bufo bufo japonicus using the vasodi1ator and vasoconstrictor agent detecting method. As a result it was considered that the renal vasoconstrictor nerves are distributed from the anterior root of the spinal cord; one through the splanchnic nerve and the other through the vagus nerve，and that in the distribution of vasodi1ator nerves，one is distributed through the vagus nerve and the other coming from the posterior root of the spiral cord is distributed through the splanchnic nerve.
Lymph vessel and lymph flow
Lymph vessels of Bufo bufo japonicus exist in circumvolution around the renal arteries
and veins，but are not found within the parenchyma. Although lymph capillaries abound in the cortex of dog，they are not present in the medulla. More 1ymph flow is noted than in other organs and the sugar content is especially large.
Renal perfusion model
The author's study was made by a method in which experiments to determine lymph flow were combined with the method devised by Cullis (1906) on the basis of Nussbaum's experiments (1878) to study the functions of the glomeruius and the nephritic duct by means of perfusion experiments on the renal blood vessels of the frog. As a result，the following fndings were demonstrated. There is no threshold in sugar permeation in the glomerulus. The larger the molecules the more permeation is affected by change of pressure in the glomerular blood vessel. Carmine permeates from the renal tubles but water either does not permeate or is reabsorbed through the tubules. The amount of sugar and dyes permeated from the renal artery to the lymph vessel is larger than that from the portal vein.
Rhythmical change of kidney
Like the spleen and the intestinal tract，the kidney undergoes rhythmical voluminal
change which causes rhythmical changes in arterial and venous blood pressure. This
is considered to accelerate blood and lymph flow and diuresis.