1895 American Journal of the Medical Sciences  
In the following pages are brought together a number of forms belonging to the species B. coli communis, as well as a variety of closely related forms which have been the object of so much attention and dis¬ cussion during the past few years. They have been studied as carefully as time permitted and certain general relationships outlined which may be of service to future systematists. Attention has been specially directed toward their behavior in fermentation-tubes containing sugarbouillon. The
more » ... sugarbouillon. The sharp distinctions brought out by this procedure between many of these forms on the one hand and B. coli and B. typhosus on the other are, to say the least, a relief from the uncertainty of the usual potato-culture and the variable intensity of the indol-reaction. These distinctions are emphasized in the following pages not for the purpose of making them the sole basis of classification, but to call attention to the necessity of applying the fermentation-test more accurately than has been done hitherto. A careful perusal of these pages will, I believe, convince the reader that the ordinary means of determining the pro¬ duction of gas are all but useless in the differentiation of related forms. In several former publications1 the writer has pointed out the value of the reaction of bacteria in the presence of carbohydrates as a means of differentiation. This is now generally conceded. All that is needed is to apply this test more precisely. In the fermentation-tube, when carbohydrates are present, the diagnostic characters exhibited by bacteria are not exhausted by the production of gas. There should always be taken into consideration: 1. The evolution of gas as to (a) total quantity, (b) rate of accumula¬ tion, (e) approximate composition, (d) temperature most favorable. 2. Formation of acids. 3. Behavior toward different carbohydrates. This scheme indicates on the surface a large amount of work. As a matter of fact, there is little more work involved than in the exhaustive study of an ordinary bouillon-culture. The handling of the tube itself requires a little more care, but if the various minor suggestions laid down in the article above referred to are heeded, no difficulty will be ex¬ perienced. The writer is fully aware of the fact that since his first publication on the use of the fermentation-tube much has been done in determining
doi:10.1097/00000441-189509000-00006 fatcat:v7hpxjyorfh6tc42zteyfp6lrq