��POPULAR SCIENCE MONTHLY.
��will need all the powers of careful observa- tion and industrious recording of which a scientific man is capable. But while I em- phatically regard these and similar problems as worthy the attention of botanists, and recognize frankly their commercial impor- tance, 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 sci- entific problems that I think it no valid argu- ment 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 at- tempt 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 re- searches are more valuable to commerce the less we are concerned with it."
Some New Facts regarding least. — 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 fermen- tation 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 ex- ample of ordinary enzyme action of special complexity. These views were partially sup- ported by some experiments of Dr. E. Buch- ner, 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 pres- sure of from four hundred to five hundred at- mospheres a liquid which, after thorough fil- tering, 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 fer- mentation in solutions of suitable sugars. The addition of chloroform, even up to the saturation point, does not inhibit the fer- mentative process, and this, in conjunction with the fact that the activity of the solu- tion is not affected by the presence of the ordinary antiseptie substances, and that the solid residue, after evaporation at low tem- peratures, is found to yield an active solution even after being kept for two or three weeks, seems to show conclusively that the fermen- tation 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 devel- opment, still yields an active solution when treated with a sterilized thirty-seven-per-cent sugar solution.
Thirteen Tears' 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 thir- teen years since the association previously met in Canada, and dealt largely in techni- calities. The progress consists partly of the continuation of investigations previously be- gun, 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 Hurthle and Tigerstedt, of Roy and Adami, and others have left us wiser on this subject than be- fore. 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 concern- ing which knowledge has advanced are those of the nature of secretion and of transuda. tion, concerning which controversies have raged that have not been wholly unprofit. able. Included in the new subjects of re- search are physiological chemistry in gen-