Generic Characters in the Coccaceae 157 



extreme, preparations will yield varying results, showing some cells 

 stained and others decolorized. As a rule, the large majority of 

 cells in a given preparation will show one reaction or the other; 

 but a second slide made from a similar doubtful case might yield 

 a different result. 



The time chosen for decolorization is, of course, an arbitrar}' 

 factor which will affect the proportion of positive results obtained. 

 In our work, as a result of Mr. Brant's experiments, we fixed on 

 three minutes, although we are not certain that this is really pref- 

 erable to the five-minute period fixed by the Committee on Standard 

 Methods. We have applied the anilin-oil-gentian-violet for one 

 and a half minutes, and the Gram solution for one and a half minutes 

 instead of the one- and two-minute periods of the committee. 



In all cases we made the stain on young 20° agar cultures (not over 

 five days old), and in each case the test was made in duplicate at 

 different times. When the results of the two tests coincided, the culture 

 was recorded as positive or negative. Cultures which gave one posi- 

 tive and one negative test, or in which the stained and decolorized 

 appeared in about equal proportions, are recorded in an intermediate 

 class. 



Flagella. — As a result of the work of Ellis (1902), we have devoted 

 considerable time to the study of motility among the cocci. This 

 author reported the finding of spores and flagella in various strepto- 

 cocci and sarcinaj, and Arthur Meyer carried this position to an 

 extreme in the statement that " the researches of Ellis have rendered 

 it doubtful whether there are any species of bacteria which entirely 

 lack flagella" (Meyer, 1903). We examined a number of cultures 

 very carefully, transferring them at frequent intervals on different 

 media, according to the general plan adopted by Ellis. We found 

 in almost every case active vibratory movements, with a tendency 

 to incomplete rotation, the successive jerks sometimes producing a 

 gradual translation across the field. This type of behavior is 

 entirely different from the true motility characterized by slow, steady 

 revolution, which appears in such forms as S. agilis. We are con- 

 vinced that most of the cocci are non-motile, while a few forms show 

 true movement; it is with this type of motility that clearly stainable 

 flagella have been found associated. The study of this character is 



