than one hundred per cent., on account, perhaps, of the oxygen molecules being unbridled.
THE WISCONSIN AGRICULTURAL EXPERIMENT STATION.
The seventh annual report of the Wisconsin Agricultural Experiment Station is a notable example of a class of literature which is rapidly increasing in extent and in popular interest. The reports of this station have become widely known for the important contributions which they contain and for their interest to those who follow the progress of science, as well as to the progressive farmer, whose needs are kept constantly in view. The last report, which is for the year ending June 30, 1900, is fully up to the standard of previous reports. It adds another chapter to the interesting studies on the process of cheese ripening or curing which Dr. Babcock and Dr. Russell have been conducting for a number of years. In the past their studies have led to the discovery of a natural enzym in milk which has been shown to be an active agent in the digestion of the proteids of cheese, rendering them soluble and digestible. This discovery, which was contrary to the prevalent bacterial theory and was opposed by many bacteriologists, has stood the test, and the theory is now generally believed in, the main point at issue being the extent and the exact character of the changes which the ferment induces. The present report takes up the action of another ferment in cheese, namely, rennet which is added during the process of manufacture. There has been much diversity of opinion as to whether the rennet had any part in the ripening process, but very little real investigation. The most recent writings on the subject have disclaimed any action due to rennet. Babcock and Russell now show that rennet undoubtedly assists in peptonizing the casein of cheese, the active agent being the peptic enzyms contained in the rennet extracts. The investigation is a quite comprehensive one, involving a study of the action of pure pepsin as compared with rennet, the conditions of the acidity most favorable to the action, and the nature of the products. The matter is of considerable importance, since it is found that the amount of rennet used influences the rapidity and the thoroughness of the ripening process. The wonder is that a point upon which there has been such marked discrepancy of opinion has not been given a thorough investigation before this.
Of equal interest is the investigation of the cause and character of the changes in green fodder when preserved as silage in the silo, also by Drs. Babcock and Russell. The generally accepted theory of silage formation as fermentation changes, due to the action of bacteria and molds, is found to be erroneous, inasumuch as good silage was made under conditions which positively precluded bacterial activity, i. e., in the presence of anæsthetics. With the aid of an ingeniously-devised closed-circuit respiration apparatus, the authors were able to study the gaseous products and to maintain the conditions entirely under their control. The unavoidable losses in ensiling green fodder were found to be due to the formation of water, carbon dioxid and volatile organic acids, which are produced, not as a result of the bacterial action, but as a result of the intromolecular respiratory processes of the plant tissues. The avoidable losses, on the other hand, are found to be due mainly to the decomposition of organic matter induced by the development of bacteria and molds, whose growth is greatly facilitated-by the admission of air, as a result of improper construction of the silo. The bacteria are, therefore, instead of being essential to good silage, only deleterious. In view of the extent to which silage is now prepared in this country, and the fact that the spoiled or partly spoiled silage is not only a loss but is likely to be injurious to stock, these results, which furnish a clearer under-
