CULTURAL CHARACTERS OF BACTERIA 41 



The Production of Invertin Ferments 



A certain few bacteria, according to Fermi, produce enzymes 

 which have the power of converting cane sugar into glucose. 



To a 2 per cent solution of cane sugar, to which has been 

 added 2 per cent of carbolic acid, add an equal quantity of a 

 10 days' old culture of the organism, and allow the mixture to 

 stand for several hours. It is then tested with Fehling's solution 

 for the presence of glucose. 



SCHEME FOR THE STUDY OF BACTERIA 

 Morphology 



On agar, grown . . . days at . . . C. (standard 24 hours). 



In bouillon, grown . . . days at . . . C. 



Cocci; single, staphlococci, diplococci, streptococci, tetracocci, sarcina. 



Bacilli; ovals, short rods, long rods, single, diplobacilli, streptobacilli, 

 filaments. 



Spirilli ; commas, short spirals, long spirals. 



Size ; breadth . . . /x, extreme length from ... /u, to ... /x, average 

 length . . . fji. 



Stain with standard watery fuchsin, easily or with difficulty, uniformly or 

 irregularly. Record size as above. Stain by Gram's method. Stain by 

 Lb'wit's method, and record size as above. Note capsule, form and size. 

 Make drawings. Note presence or absence of flagetla ; length, structure, 

 arrangement, numbers ; monotrichic, lophotrichic, peritrichic. 



Motilily ; sluggish, active, rotatory, progressive. 



Spores, presence or absence ; form, size, location, effect on mother cell ; 

 clostridium, clavate, or capitate forms. Stain by Abbot's method. Heat 

 a small portion of an old agar or potato culture, suspended in bouillon, 

 for 10 minutes at 80 C., and determine vitality. 



Spore germination ; polar, equatorial, by absorption. 



Pleomorphism on media of different reaction, and of different kind. 



Relative growth at 20 and 37 C. Thermal death point in ... minutes. 



Optimum temperature . . . C. Growth limits, maximum and minimum. 



Relative growth in -f r.5, 1.5, and o bouillon. 



Gelatin Colonies 



Deep colonies ; form, edges, size, color, internal structure. 

 Surface colonies ; form, surface elevation, internal structure, edges, optical 

 characters. 



