will need all the powers of careful observation and industrious recording of which a scientific man is capable. But while I emphatically regard these and similar problems as worthy the attention of botanists, and recognize frankly their commercial importance, I want carefully and distinctly to warn all my hearers against supposing that their solution should be attempted simply because they have a commercial value. It is because they are so full of promise as scientific problems that I think it no valid argument against their importance to theoretical science that they have been suggested in practice. In all these matters it seems to me we should recognize that practical men are doing us a service in setting questions, because they set them definitely. In the attempt to solve these problems we may be sure science will gain, and if commerce gains also, so much the better for commerce and indefinitely for us. But that is not the same thing as directly interesting ourselves in the commercial value of the answer. This is not our function, and our advice and researches are more valuable to commerce the less we are concerned with it."
Some New Facts regarding Yeast.—Some interesting experiments have been under way during the past few years regarding the phenomena of fermentation. It has been generally thought that the alcoholic fermentation of sugar by yeast differs from the ordinary hydrolytic processes of the enzymes in that the actual presence of the living yeast cell was an essential. Some investigators have doubted this, however, and have thought that alcoholic fermentation was simply an example of ordinary enzyme action of special complexity. These views were partially supported by some experiments of Dr. E. Buchner, announced in the early spring; and it is now reported that later experiments from the same laboratory still further confirm this view, and, in fact, make it almost a certainty. Dr. Buchner, by pounding up pure yeast with quartz sand and adding a certain amount of water, was able to squeeze out under a pressure of from four hundred to five hundred atmospheres a liquid which, after thorough filtering, was of an opalescent appearance and possessed an agreeable yeastlike odor. All care was taken to exclude any organism from the liquid, and it was found that under these conditions it was able to excite alcoholic fermentation in solutions of suitable sugars. The addition of chloroform, even up to the saturation point, does not inhibit the fermentative process, and this, in conjunction with the fact that the activity of the solution is not affected by the presence of the ordinary antiseptie substances, and that the solid residue, after evaporation at low temperatures, is found to yield an active solution even after being kept for two or three weeks, seems to show conclusively that the fermentation in these cases is not brought about by living protoplasm in any form, but is really due to an enzyme ferment which the author calls zymase. This is further confirmed by the fact that dried yeast heated to 100° for six hours, while incapable of further development, still yields an active solution when treated with a sterilized thirty-seven-per-cent sugar solution.
Thirteen Years' Progress in Physiology.—The presidential address of Prof. Michael Foster in the Physiological Section of the British Association was devoted to a review of the progress of physiology during the thirteen years since the association previously met in Canada, and dealt largely in technicalities. The progress consists partly of the continuation of investigations previously begun, and of advance in investigations newly entered upon. An example of the former kind is the study of the mechanics of the circulation. The researches of Hürthle and Tigerstedt, of Roy and Adami, and others have left us wiser on this subject than before. So real, if not exciting, progress has been made with the problems of muscular contraction; we are some steps measurably nearer an understanding of what is the nature of the fundamental changes that bring about contraction, and what are the relations in the changes in the structure of muscular fiber. In respect to the beat of the heart, we have continued to approach nearer to the full light. Among other problems concerning which knowledge has advanced are those of the nature of secretion and of transudation, concerning which controversies have raged that have not been wholly unprofitable. Included in the new subjects of research are physiological chemistry in gen-
