132 CONN, HARDING, KLIGLER, FROST, PRUCHA AND ATKINS 



adapted to its growth. Under such circumstances invigorate by 

 the procedure just outlined but using the medium and tempera- 

 ture found most favorable for the organism in question, recording 

 on the chart the method of invigoration adopted. If no condi- 

 tions are known under which the organism in question produces 

 vigorous growth, it should be studied without preliminary culti- 

 vation as soon as possible after isolation from its natural habitat. 

 Such an organism is not likely to give good growth on any ordi- 

 nary media, and the results of the study called for by the chart 

 will have little significance. 



STUDY OF MORPHOLOGY 



The routine study of morphology should be from dried prep- 

 arations, stained with fuchsin, methylen blue, or gentian violet. 

 Preparations to show the vegetative cells should be made, pref- 

 erably, from agar slant cultures, from a few hours to two days 

 old, according to the rapidity of growth. The medium and tem- 

 perature used and the age of the culture should be recorded. 



Motility. Hanging-drop preparations of young broth or agar 

 cultures should be examined for motility. If motile, microscopic 

 preparations should be made to show the arrangement of the 

 flagella, using any of the ordinary methods of flagella staining 

 with which the student can obtain good success. Even if mo- 

 tility is not observed in hanging-drop, it is wise to attempt a 

 flagella stain, because motile organisms often lose their motility 

 under the conditions of observation. Even negative results from 

 both hanging-drop preparation and flagella stain do not absolutely 

 prove that the organism is immotile. 



Presence of spores. Routine examinations for spores should be 

 made on stained, dried preparations from agar slant cultures a 

 week old. Stain with methylen blue. Vegetative forms take the 

 stain, but spores do not. In most cases there will be no trouble 

 in finding spores if the organism produces them. All rather 

 large rods however, (0.8 micron or more in diameter) should be 

 regarded as possible spore-producers, even though microscopic 

 examination does not show spores. Such bacteria should be 



