I02 MANUAL OF BACTERIOLOGY. 



14. Production of gas in fermentation-tube with bouillon 



containing sugar, as dextrose, or in agar with sugars. 



15. Potato. 



16. Blood-serum; observe whether or not peptonization 



occurs. 



17. Production of indol. 



18. Pigment formation. 



19. Production of acid or alkali. 



20. Relation to oxygen; observe whether the superficial 



or the deep part of the growth is the more luxuriant 

 in stab-cultures; use anaerobic methods if necessary. 



21. Pathogenesis. 



In commencing the study of bacteriology the pupil should try 

 the common staining methods and make the most important 

 culture-media. Having culture-media prepared, it is customary 

 to study a number of species of non-pathogenic bacteria. Notes 

 of the work and sketches showing the morphology of the organ- 

 isms should be made. In this as in other work with the micro- 

 scope, the value of even crude drawings is very great as a matter 

 of training. It is well to choose species which have properties 

 decidedly different from one another. The micrococci, bacilli 

 and spirilla should be represented; forms that are motile and 

 that are not; species that form spores and others that do not 

 form spores; some that liquefy gelatin and some that do not. 

 There should be chromogenic forms, and species that ferment 

 dextrose, and that produce indol, — such species as some of the 

 sarcinae, the bacillus coli communis, the hay bacillus, the potato 

 bacillus, bacillus prodigiosus, a bacillus fluorescens and spirillum 

 rubrum. It is well, when possible, to obtain material directly 

 from nature rather than from laboratory cultures. This may 

 readily be done in the case of the hay bacillus and the potato 

 bacillus. Fecal matter may be spread on gelatin plates and the 

 bacillus coli communis obtained in pure culture. Fluorescing 

 bacilli are very common in water. Large spirilla are often found 



