The methods used up to the present to calculate the speed of the portal circulation have been the following: Serial splenoportography, the injection into the spleen of radioactive sodium and subsequently detecting its absorption by the liver, and, finally, the method of Newman and Cohen,3which consists of the injection of ether vapors into the rectum, after which the time it took to detect the smell of ether from the patient's breath is measured. The first method, the splenoportography, not only enables one to calculate the circulation time but also gives us an x-ray picture of the portal tree. The second method mentioned is a more exact one but requires a more elaborate technique, which is not easily carried out in the ordinary practice. Lastly, the procedure of Cohen and Newman has obvious inconveniences; also, one cannot be sure if the ether is readily absorbed by the intestine. Even