1 88 Theobald Smith 



fields of microbiology. The species studied some years ago 

 are assuming a more and more hazy outline and questions are 

 constantly arising concerning the possible identity of old with 

 new forms. This condition is largely unavoidable in a young 

 and rapidly growing department of science and is in part due 

 to the fact that investigators are too prone to attack new prob- 

 lems before the more orderly work concerning the old ones has 

 been completed. For this state of affairs they are hardly to 

 be blamed, for the profound relations of bacteria to other life 

 on our globe has given the study of them a practical bias 

 without which the resources now employed in investigations 

 could never have been wrested from the utilitarianism of our 

 present social organization. 



It is due to considerations such as these that this article is 

 presented as a contribution to the methods by which bacteria 

 may be more definitely recognized: A complete differentia- 

 tion is possible oxAy through a complete knowledge of the bi- 

 ology of any given organism. This knowledge is onl}' grad- 

 ually acquired and more or less teniporar\^ expedients must 

 be resorted to to fix the hosts of microorganisms shading into 

 one another by almost intangible gradations of form and func- 

 tion. Among these expedients the fermentation tube occupies 

 an important place in the differentiation of the more sapro- 

 phytic forms and in giving us a fairly good conception of their 

 powers of fermentation. I can do no better therefore in com- 

 memoration of the present occasion than to ofi"er the observa- 

 tions which I have made with it during the past four j^ears, as 

 a connected whole to the biologist. 



The fermentation tube appears to be an apparatus of considerable 

 antiquity. The bent tube closed at one end has been used by chemists 

 in storing small quantities of gas for qualitative analysis. I have been 

 unable to determine who was the first to apply it to fermentation pro- 

 cesses. In Ti^tmitr's pfla7izenphysiologisches Pradicuin I find it figured 

 as Kiihne' sches Gdhrungsgefdss. More recently it has been adapted 

 by Einhorn' for the quantitative determination of sugar in urine and by 

 Doremus for the quantitative determination of urea in the same fluid. 

 In 1889 I conceived the idea of using this tube as an ordinary culture 

 tube in order to determine something more definite concerning the pro- 

 duction of gases by bacteria without resorting to the complex manipula- 

 tions of the chemist'. The form of the tube used in the following studv 



