484 



SCIENCE. 



[N. S. Vol. XXI. Xo. 535. 



no loss of pathogenicity resulted from this 

 long exposure to unfavorable conditions. 

 Cabbage plants inoculated with pure cul- 

 tures, obtained from seed thirteen mouths 

 after infection, showed a blackening of 

 the veinlets in the leaf and other evidences 

 of disease at the end of sixteen days. 



At a time when so much stress is being 

 laid upon the quickness with which patho- 

 genic organisms are destroyed in nature 

 these observations should tend to check 

 hasty generalizations. (To be published 

 in full in Centralhl. f. Bakteriol., etc., II. 

 Abt.) 



The Demonstration of the Flagella of 

 Motile Bacteria and a Simple Method of 

 Making Photomicrographs: Edward W. 

 DucKWALL, Aspinwall, Pa. 

 I found that the methods for flagella 

 staining described by the old authors had 

 to be modified. I divided the motile bac- 

 teria into six classes for staining purposes : 



1. Bacilli which grow like typhoid, such 

 as typhoid and colon. Bacteria resembling 

 typhoid are actively motile bacteria. The 

 material is transferred to a large drop or 

 two of distilled water, previously boiled. 

 A fine platinum loop, about half the usual 

 size, should be used. The finest specimens 

 of bacteria will swim to the outer edges of 

 the water. 



2. Bacilli which produce wrinkled or 

 folded growths, such as Mesentericus fus- 

 cus. In order to get a good prepara- 

 tion from the bacteria which produce 

 wrinkled or folded growths the agar should 

 be streaked in the morning and carefully 

 watched for the first appearance of growth. 



3. Bacilli which send out a thin, almost 

 transparent growth over the surface of the 

 agar, such as Bacillus subtilis and Bacillus 

 megatherium. In order to get a good 

 preparation from the thin, transparent, 

 spreading growth a curved platinum wire 

 is used to collect the bacteria en masse and 



transfers are made to the distilled water 

 with the small loop. 



4. Bacilli which produce slime, such as 

 Bacillus vulgatiis and Bacillus viscosus. 

 The slime which collects between the 

 flagella of the slime-producing bacteria 

 can be precipitated by shaking a water 

 suspension with chloroform. A very 

 young growth is used and transfers are 

 made to about 1 e.c. of water until it is 

 made very cloudy. This suspension is 

 then shaken with chloroform and the cover- 

 glass preparation is made from the water 

 above the chloroform. 



5. Bacilli which produce pigments, such 

 as Bacillus prodigiosus and Bacillus cyano- 

 genes. Bacteria which produce pigments 

 soluble in chloroform are treated in the 

 same manner. Those Avhose pigments are 

 soluble in water and not in chloroform I 

 prepare by holding the cover-glass under 

 the tap after fixing the preparation in the 

 flame previous to adding the mordant. 



6. Anaerobic bacteria, such as Bacillus 

 tetanus, cedema and sjonptomatie anthrax, 

 etc. The best results with anaerobic bac- 

 teria are obtained as follows: The medium 

 is two per cent, glucose agar in slants and 

 the inoculation is made back of the slant 

 between the agar and the wall of the tube. 

 I slide the needle back of the slant and let 

 it fall forward, I introduce two or three 

 drops of a young bouillon culture and re- 

 place the agar. By excluding oxygen and 

 maintaining a blood temperature for 

 thirty-six hours a fine growth is usually 

 obtained. 



I prefer the No. 1 round cover-glasses. 

 For removing the grease they are covered 

 with siilphuric acid, which is poured off 

 after they have stood one day, and they 

 are then covered with bichromate of potas- 

 sium. After several hoiars this is poured 

 off and they are washed Avith distilled 

 water and transferred to a jar containing 

 absolute alcohol, where they remain until 



