KOCH'S SOLID MEDIA 43 



originally used for obtaining the material being then pressed against the 

 sides of the test-tube to express excess of fluid and then stroked gently 

 over successive lines on one plate. Or, if the organisms be very abun- 

 dant, 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 locp. 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 one 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. 



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. 



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, in- 

 stead of the single generic name and single specific one as is used in 

 zoological nomenclature. This matter of nomenclature is a subordi- 

 nate 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) 

 and consequently at a time when the isolation of organisms in pure 

 culture was a matter of extreme difficulty and uncertainty. One of 

 the first facts noted by the student in taking up bacteriology is the 

 difficulty in determining motility; this property should always be 

 tested on young cultures in bouillon. In Brownian movement there 

 is a sort of scintillating movement, but the bacterium does not move 



