NON-PATHOGENIC BACTERIA. 161 



colored covering which lasts for years. The rods are slender, with 

 rounded ends, and produce small oval spores. It grows upon agar 

 and liquefies gelatin. 



V. Proteus Vulgaris. 



Proteus vulgaris is found in putrefying animal matter; is a facul- 

 tative anaerobic motile saprophyte; has rods with rounded ends, 

 which grew into flexible filaments; produces a whitish growth on 

 agar, and liquefies gelatin; forms H 2 S, and causes putrefaction, oc- 

 casionally being pathogenic to man. 



VI. Micrococcus Urese. 



This species may be obtained from cystitic and decomposing urine. 

 The cocci occur singly, in pairs, or in filaments. It is an aerobic 

 saprophyte, grows readily at room temperature, and does not liquefy 

 gelatin. Plate cultures appear like a drop of wax upon the sur- 

 face. 



VII. Sarcina Lutea. 



Sarcina lutea may be obtained from the air. It is an aerobic 

 chromogenic species, whose cocci occur in 'pairs, tetrads, and pack- 

 ets. The pigment is yellow. It liquefies gelatin slowly. 



VIII. Spirillum Rubrum. 



This is a motile chromogenic facultative anaerobic species. It 

 may be found in the putrefying cadaver of a mouse. The spirals 

 make three-quarter turns. It groAvs on agar, stab cultures, form- 

 ing a red pigment. 



Laboratory exercise No. 54. Bacillus subtilis. Prepare a pure cul- 

 ture of this species and inoculate tubes of agar and gelatin. Make a 

 study of the growths upon these media, describing- each. Make a water- 

 mount and demonstrate the motility of the rods and filaments. Make a 

 cover-glass preparation and stain with gentian-violet, method No. 10. 

 Demonstrate flagella, staining by method No. 13. Demonstrate spores 

 by method No. 12. Prepare an outline of this species as indicated on 

 page 155. Make drawings of cultures and rods. 



Laboratory exercise No. 55. Micrococcus ureae. Obtain plate cultures 

 from decomposing urine. Note the wax-like colonies. Make a cover- 

 glass preparation and stain with gentian-violet. Observe the spherical 

 cells arranged singly, in pairs, and in chains. How does this species 

 11 



