OBJECTIVES

The chemical end-products of bacterial metabolism have been used since the early days of the science as a means of classifying bacteria; and systematic bacteriology rests in large part upon such determinations. In recent years the unique advantages offered by bacteria for the elucidation of the basic problems of cell physiology have been increasingly recognized. The study of bacterial metabolism in the past has generally been concerned either with the products of protein metabolism (summarized by Rettger (1928)) or with the products of carbo-hydrate metabolism (reviewed by Kendall (1928)). In the former case, analyses of the medium give at least a fair picture of the situation. In carbohydrate metabolism, on the contrary, the acidity of the medium may, as shown by Merrill (1930) for mycobacteria, bear no relation whatever to actual decomposition of sugars. On the other hand, the study of carbon dioxide pro-duction in the Smith fermentation tube or in similar pieces of apparatus can only permit the most general conclusions. A