TYl'F.S OF BACTERIA FOUND IN MILK 27 



should, however, be explained. The organism in question ap- 

 pears commonly in the form of a short, non-motile rod, which is 

 not infrequently divided into two, as shown in figure 15, c, giv- 

 ing the form known as the diplococcus. When it appears in 

 this form, the question arises whether it is not more properly 

 called one of the coccus type than a Bacterium. The longer 

 forms, as shown in figures 14 and 15, may simply represent the 

 cocci, elongating and about ready to divide. If this is the case, 

 the organism should not be called a Bacterium, which term is, 

 as we have seen, applied to* rods, but rather Streptococcus, 

 which is the name given to' 

 spherical forms having one 

 division plane. (See p. 13.) 

 If it is a coccus form it 

 should be called Streptococ- 

 cus ; then the name Strepto- 

 cocci lactarius is the cor- 

 rect one to adopt. 1 If, 

 however, the organism is 

 regarded as a short rod, 



then the term Bacterium should be applied, and the name 

 Bact. lactis acidi should be used. 2 It may seem strange that 

 bacteriologists cannot agree as to whether this most com- 

 mon milk organism is a Bacterium or a Streptococcus, but 

 the fact is, that there is no sharp criterion by which the 

 microscopist can tell whether he is dealing with an extremely 

 short rod or a spherical form that is slightly elongated just be- 

 fore division. The same culture of bacteria from which figure 

 14, d, was drawn was submitted to two microscopists, one of 

 whom called it a 'Coccus and the other a Bacterium. Because 

 of this difficulty in finding any sharp distinction between the 

 two, it has been impossible to state with absolute certainty 



FIG. 



14 VARIETIES OF BACT. LACTIS 

 ACIDI (CONN) 



1 Kruse. Cent. f. Bact. II., xxxiv., p. 737, 1903. 



sheichmann. Cent. f. Bact., II., pp. 281 and 777, 1896; V. f p. 344, 1899. 



