DESCRIBING AN 0B6ANIS3f. Til 



by tests on a portion of the same medium not inocu- 

 lated, as some of the ingredients of which the medium 

 is composed may contain nitrites. Lunkewicz recom- 

 mends the use of Merck's peptone for this test, claim- 

 ing that nitrites are always to be found in Witte's 

 peptones. 



POINTS TO BE OBSERVED IN DESCRIBING AN ORGANISM. 



The following is an outline of points to be considered 

 in describing a new organism or in identifying an 

 organism with one already described : 



1 . Its source — as air, water, or soil. If found in the 

 animal body, is it normally present or only in patholog- 

 ical conditions? 



2. Its form, size, mode of development, occurrence 

 of involution-forms or other variations in morphology. 

 Grouping, as in pairs, chains, clumps, zoogloea; pres- 

 ence of capsule ; development and germination of 

 spores ; arrangement of flagella. 



3. Staining-peculiarities — especially its reactions with 

 Gram's (or Weigert's fibrin) stain, and peculiar or irreg- 

 ular modes of staining. 



4. Motility — to be determined on very fresh cultures 

 and on cultures in different media. 



5. Its relation to oxygen — Is it aerobic, anaerobic, 

 or facultative? Does it develop in other gases, as 

 carbonic acid, hydrogen, etc. ? 



6. Both the macroscopic and microscopic appearance 

 of its colonies on nutrient gelatin and on nutrient agar- 

 agar. 



7. The appearance of its growth in stab- and slant- 

 cultures on gelatin, agar-agar, blood-serum, and potato. 



