8 THE AMERICAN MO:NTHLY [January, 



are observed. I have obtained my best results with a culture about 

 two days old. The surface of agar seems preferable to gelatine for cul- 

 tivating bacteria for this purpose. 



In testing the various methods and their modifications I have stained 

 the flagella on a considerable number of bacteria, among which I will 

 mention a large motile bacillus quite common in Potomac water, the 

 Bacillus Jiuorescens liquefaciens^ and the Bacilhis coli communis. 

 The last of these, like the Typhoid bacillus^ is provided with rings of 

 flagella, and consequently belongs to the Peritricha. The flagella on 

 each of these species have been stained by the use of both an alkaline 

 and an acid mordant. 



Although a large amount of work has been done to develop satisfac- 

 tory methods for staining the flagella on motile bacteria, there seem to 

 be many conditions that are not yet fully understood. These must be 

 carefully woi-ked out by actual experiment before we will be able to 

 determine accurately the specific character of the flagella on the tliflcrcnt 

 species of bacteria. 



No flagella have been found on the swine plague and other non-motile 

 bacteria, although a very large number of specimens have been stained 

 by the same methods that I have successfully employed with the motile 

 forms. This, together with the fact that with certain inotile bacteria 

 at least a few flagella can be seen in every stained preparation, elimi- 

 nates from the writer's mind the doubt that has occasionally been ex- 

 pressed, that the long wavy or spiral filaments seen to radiate from the 

 bacteria or lying between them do not belong to the germs with which 

 they are associated. 



I am indebted to Dr. Theobald Smith for suggestions which he has 

 offered from time to time during the prosecution of this work. 



Bibliography. 



1 . Cohn, F. Untersuchungen uber Bacterien. Beilriige zur Biologic der Pflcut- 



ze7t. Bd. I (1872), p. 126. 



2. Dalli>iffci\ W. H., atid Drysdale, J. J. On the existence of Flagella in 



Bacterium Termo. T/ie Monthly Microscopical yonrual (London). 

 Vol. xiv (1875), p. 105. 



3. DnUinger, \V. 11. On the Measui-ement of the Diameter of the Flagella 



of Bacterium Termo. Jour, of the Royal Mic. Society. Vol. i (1878), 

 p. 169. 



4. Koch, Robert. Untersuchungen Uber Bacterien. Beitrage zur Biologic der 



Pfianzcu. Bd. II (1877), P- 4i<^ 



5. Neuhaiiss, R. Ueber die Gisselen an den Bacillen der Asiatischen Cholera. 



Centralblatt f. Bakteriologie u. Parasitcnkiuide. Bd. V (18S9J, p- 81. 



6. Loeffler, F. Ein neue Methode zum Farben der Mikro-organismen im be- 



sonderen ihren Wimperhare und Geis-seln. Ibid. Bd. VI (1889), p. 

 209. 



7. Locffcr, F. Weitel-e Untersuchungen iiber die Beizung und Farbung der 



Geisseln bei den Bakterien. Ibid. Bd. VII (1890), p. 625. 



8. Tre>ikmaii?i, Dr. Die Farbung der Geisseln von Spirillen und Bacillen. 



Ibid. Bd. VI (1889). p. 433. 

 8. Troikmauii, Dr. Die Fiirbung der Geisseln von Spirillen und Bacillen. 

 Ibid. Bd. VIII C1890), p. 385. 



10. Doivdeszvell, G. F. Note sur les Flagella der microbe der Chok'ra. A71- 



nitlcs do Micrografhic. T. II (1890), p. 367. 



11. Smith, Theobald. Einige Bemerkungen Uber Saure und Alkalibildung bei 



Bakterien. Cetitralblatt f. Bakteriologie u. Parasitenliunde. Bd. VIII 

 (^1890), p. 389. 



12. Moore, V. A. A review of the methods of Demonstrating the Flagella on 



