194 BACTERIOLOGY. 



The different characters of an organism may be 

 grouped as : (a) morphologic, those ascertained by exam- 

 ination of the individual organism under a lens of high 

 magnifying power; (6) biologic, those ascertained by 

 macroscopic and microscopic study of the gross appear- 

 ance of the culture in the different media; (c) biochemic, 

 the alterations produced in the different media as shown 

 by direct examination or by the use of different reagents ; 

 and (d) pathogenic, the effects of the inoculation of the 

 culture into susceptible animals. 



SCHEME OF STUDY. Record the source from whence 

 the organism was derived. Was this the normal habitat 

 of the organism, or was it present accidentally ? 



MORPHOLOGIC CHARACTERS. Note the shape, size, 

 and grouping of the organism as it occurs in the differ- 

 ent media. Observe the nature of the ends of the indi- 

 vidual organism. Determine the presence or absence 

 of motility in very young cultures. If motility is 

 observed, apply one of the special methods for demon- 

 strating flagella to note their relative number and loca- 

 tion. Stain young cultures by means of the different 

 staining solutions, and note the effect of each. Do the 



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organisms stain deeply and uniformly, or are they 

 stained in a peculiar manner? Apply the Gram method 

 of staining, and note whether or not the organisms 

 are decolorized by the alcohol. Stain the organisms 

 deeply with carbol-fuchsin staining solution, and note 

 the effect of different decolorizing agents ; and ascertain 

 whether the organisms are capable of resisting the 

 decolorizing effects of dilute acids. Do the organisms 

 show the presence of a capsule when taken from the 

 blood or tissues of an animal, or when taken from cult- 

 ures in milk or blood-serum ? Examine cultures that 



