Page:Popular Science Monthly Volume 60.djvu/101

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THE PROGRESS OF SCIENCE.

dissertations. The more important facts and conclusions were, however, collected and presented in organized form in a series of lectures delivered at the Institute for Experimental Medicine. These lectures, originally published in Russian, have been translated into German and issued in book form ('Die Arbeit der Verdauungsdrüsen,' Wiesbaden, 1898; J. F. Bergmann). They have been widely read and have received abundant praise everywhere. The chief merit of Pawlow's work lies in the application of new experimental methods to the solution of important problems in the physiology of secretion and digestion. Thus the introduction of the combined œsophageal and gastric fistulas has led to original observations on the mechanism of secretion; while the possibility of obtaining pure gastric juice has given rise to renewed chemical investigation of the composition and properties of this secretion. By an ingenious method of isolating completely a portion of the stomach while keeping unimpaired the nerve distribution to the isolated part, still further advances have been made. Other methods have been applied by Pawlow to the study of the function of the pancreas and the production of the bile. The specific influence of the nervous system on secretion, and the paths along which this is exerted, have been ascertained more definitely than ever before. Pawlow's contributions to experimental technique in these departments of investigation are unique, and their influence is already shown in the renewed interest which they have aroused lately in the study of digestion in general. To the more purely chemical aspects, also, this brilliant investigator has directed his attention. A prominent German physiologist has remarked that so many noteworthy results have not been achieved by any single investigator (together with his pupils) since Beaumont and Blondlot, and, in more recent years, Heidenhain.

In addition to these researches, mention may be made of the splendid investigations on the seat of urea formation in the animal body, which were carried out conjointly with Professor Nencki. Here again it was the application of new experimental methods—the Eck fistula operation, by means of which direct communication is established between the portal vein and the vena cava in mammals—which inaugurated a fresh series of important contributions on the rôle of the liver in intermediary metabolism.

Aside from the clear analysis of the problems involved and the originality of the methods applied, accurate observation and unremitting energy characterize Professor Pawlow's work. Every result obtained is verified until it stands as a permanent fact. Physiologists will rejoice at the fitting recognition which such successful achievements have received.

ZINC IN DRIED FRUITS.

During the past few years the export of dried apples and other fruit from this country to the continent of Europe has been greatly interfered with by the presence of zinc; the discovery of traces of this metal in the fruit has been deemed sufficient ground for prohibiting its importation. The presence of the zinc has been accounted for by the zinc trays used in the fruit driers, but the abandonment of the metal for this purpose has not sufficed to free the fruit from suspicion. A service has been rendered American fruit growers by an investigation recently carried out by Herr Soltsien, of Görlitz. He was incited to this by the detection of quite a strong trace (0.0067 %) of zinc in some American 'evaporated apples,' which had evidently not been dried on zinc trays. He finds that when zinc is present in the soil or in the atmosphere, it is readily taken up by plants, and, by consumption of such contaminated vegetables and fruit, even into the human body.