50 STUDY AND IDENTIFICATION OF BACTERIA 



over successive lines on one plate. Or, if the organisms be very abundant, over a 

 second plate without recharging it from the inoculated tube. 



According to my experience a very satisfactory method is to take a loopful from 

 the bouillon tube suspension of the pus or faeces and deposit the fluid in the platinum 

 loop on the left half of the poured plate then, without recharging the loop, we touch 

 the right half of the plate. Now taking a bent glass rod from a jar of 95% alcohol 

 we flame it and to cool the same we press the bent portion into the middle of the 

 plate. This also divides the surface of the plate into two portions. Then rubbing 

 the bent rod over the smaller amount of the material on the right side we carry it over 

 the entire right side. Then go to the loopful deposited on the left side with the rod 

 and rub it over this side. For urine, deposit i drop on one side and 5 drops on 

 the other. A smear from pus, sputum, urine or throat culture should always be made 

 first in order to get an idea as to the degree of dilution which is necessitated before 

 plating out. We use blood agar plates as routine ones when we culture from 

 throat, glands, joints, pus, blood, etc. The lack of translucency does not interfere 

 when we study the morphology of superficial colonies, using a hand lens. Then 

 the haemolytic zone of S. pyogenes or the green of S. viridans or the Pneumococcus 

 make such a medium indispensable. All pathogens grow well on it. For faeces 

 we use Endo's medium. 



Esmarch's Roll Culture Tubes. Having melted about 5 c.c. agar in a test- 

 tube we inoculate the melted medium at 45C. and very quickly roll the tube in 

 a groove melted out of a block of ice. The agar sets on the sides of the tube and 

 colonies may be studied with a glass. Such tubes form a large amount of water 

 of condensation which aids in the study of streptococci. By inoculating as above, 

 heating to 8oC., then rolling and filling the tube with liquid petrolatum we have 

 a simple method for anaerobes. Larger tubes with rolled media are useful for 

 culturing bacterial growth for vaccines, this technique giving a larger surface 

 than the slant. 



To obtain isolated colonies on blood-serum or blood-streaked agar, 

 which can be touched and by transfer obtained in pure culture, we 

 simply smear the material on a slant of either medium. Then, without 

 sterilizing the loop, we smear it thoroughly over a second slant, and so 

 on to a third, or possibly a fourth or fifth. 



Classification. At present the classification of the bacteria is very unsatisfactory 

 from a scientific standpoint. The nomenclature abounds in instances where three 

 or four terms are used in naming a single bacterium, instead of the single generic 

 name and single specific one as is used in zoological nomenclature. This matter of 

 nomenclature is a subordinate factor in the confusion when we begin to investigate 

 and find that different names have been applied to apparently the same organism. 



The slightest variation in morphological, locomotor, or biological 

 characteristics seems to be considered sufficient by many observers to 

 justify the description of a new species, and, of course, the giving of a 

 new name. Many of these names which are now retained were applied 

 prior to the epoch-making introduction of gelatin media by Koch (1881) 



