About thirty distinct experiments were tried on ten different animals, with only two or three negative results to fifty positive ones. The results, taken collectively, plainly indicate that the increase in the number of leucocytes in the circulating blood, after the ingestion of food, is very marked, the maximal increase being 146 per cent., while the average increase amounted to 78 per cent. This, as Pohl states, would indicate for the total content of blood in an animal an increase in some cases of 1,000,000,000 of leucocytes. Control experiments showed that, normally, there were only comparatively small variations in the content of leucocytes in the blood, from hour to hour, in the absence of food. It is to be further observed that this marked increase in the number of white corpuscles in the circulating blood, after the ingestion of food, usually reaches its maximum in the third hour, _viz._: at a time when digestion would most probably have reached its height, no noticeable change being usually observed before the end of the first hour after the taking of food. Evidently, some transformation-products of the ingested food must be formed before leucocytosis becomes marked. The return to the normal number of leucocytes shows no regularity; in some cases being very gradual, in others quite rapid. This marked action of food in increasing the number of leucocytes in the circulating blood, naturally raises the question whether all varieties of food possess this power, or whether it is limited to some one or more individual food-stuffs. In attempting to answer this question, Pohl tried a large number of experiments, the results of which afforded proof that neither water, salts, fats, carbohydrates, or even meat extracts, are able to materially affect the number of leucocytes in the blood. Proteid-containing foods, on the other hand, such as meat, Witte’s peptone, and gelatin peptone quickly raise the content of white blood corpuscles to a marked degree. Somewhat noticeable was the result obtained on feeding wheat bread. This food-stuff, in spite of its fairly large content of proteid matter, failed to exert any influence on the number of leucocytes in the blood, and in conformity with this result it was found that in herbivorous animals there was an utter lack of anything approaching a digestive leucocytosis, even after protracted fasting.