180 BACTERIOLOGY 



The different characters of an organism may be grouped 

 as: (a) morphologic, those ascertained by examination of 

 the individual organism under a lens of high magnifying 

 power; (6) biologic, those ascertained by macroscopic and 

 microscopic study of the gross appearance of the culture 

 in the different media; (c) biochemic, the alterations pro- 

 duced 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 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 different media. Observe the nature of the 

 ends of the individual 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 location 

 and do not be discouraged if your first attempts fail. Stain 

 your cultures by means of the different staining solutions, 

 and note the effect of each. Do the 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 



