548 ^^6 Philippine Journal of Science isia 



Penfold -' succeeded in "training" typhoid to increased fermenta- 

 tive power in isodulcite. 



In the race of dysentery bacilli experimented on by me, it is 

 evident that contact with maltose is not necessary to the for- 

 mation of the maltose ferment, since an ordinary agar culture 

 of a race which had never been in contact with maltose gave, 

 of single isolated bacilli, about 25 per cent of maltose fer- 

 menters, approximately sixty-five days after isolation from the 

 patient, and about 13 per cent after culture on agar for five 

 months. It may be that the agar used contained some substance 

 which might replace maltose as an excitant of a maltose ferment, 

 but it is more probable that in this case variations in fermenta- 

 tive character occur without a special food stimulus. Again, in 

 this race of dysentery, growth in contact with maltose did not 

 materially increase the proportion of maltose fermenters, unless 

 kept for a long time in the same tube. Several series of ex- 

 periments were carried out to test this matter. 



In series 1, an alkaline and an acid-forming race were carried 

 through 15 successive daily transfers on 3 sorts of broth: the 

 first containing 1 per cent peptone, 0.5 per cent salt, and 1 per 

 cent maltose; the second having the same ingredients with 

 mannite instead of maltese ; and the third consisting of ordinary 

 beef-peptone broth. Cultures were tested on litmus-maltose agar 

 slopes. At the end of the series the acid remained acid as 

 before and the alkaline remained alkaline with no increase in 

 the proportion of secondary maltose-fermenting colonies. 



In a second series, an alkaline race, which had never grown 

 on a maltose medium, was cultivated fifteen days; in one lot 

 with daily transfers and in the other with transfers at intervals 

 of three days, a period of time sufficient for allowing the for- 

 mation of secondary colonies on maltose agar. Six different 

 media were used: One, a broth containing peptone, 2.5 grams; 

 sodium phosphate, 2.5 grams ; calcium chloride, 5 cc. ; asparagin, 

 5 CO.; maltose, 10 cc. ; water, 1,000 cc. ; 2, the same as 1, plus 

 enough agar to make a soft medium; 3 and 4 the same as 1 

 and 2, respectively, but containing no sugar; 5, ordinary beef- 

 broth peptone; 6, ordinary agar. Cultures were tested daily 

 on maltose-agar slopes. At the end of the series both lots, the 

 one transferred daily and the one transferred every three days, 

 remained the same as at the start, except that the ordinary 

 agar one showed some, although not a constant, tendency to 

 become more acid. Since there was some suspicion that the 



'"Jovrn. Hijg., Cambridge (1911), 11, 30. 



