776 



SCIENCE. 



[N. S. Vol. IV. No. 100. 



unfavorable conditions. Typhoid faeces 

 were kept in the glass- stoppered bottles 

 in which they were received, and plates 

 made from time to time to ascertain 

 whether the fermenting function of the 

 colon bacillus is affected by prolonged resi- 

 dence in such a medium. 



Of twenty series tested, three, covering a 

 period of 126 days, are tabulated (see table) . 



Series A : This series consists of cultures 

 from fresh typhoid faeces. The gas forma- 

 tion with glucose is typical, but with lac- 

 tose and saccharose the amount is con- 

 siderably diminished. 



Series B: These cultures were made from 

 the same specimen of faeces when it had 

 been kept for thirty days. They show a 

 great reduction in the amount of gas pro- 

 duced with each variety of sugar. No. 2 

 does not form gas with either form of sugar, 

 and does not coagulate milk, yet in indol- 

 formation, growth on potato, motility and 

 macroscopic and microscopic appearance it 

 is like the typical colon bacillus. Number 

 4 gives merely a bubble of gas with lactose 

 and saccharose. 



Series C: This series was obtained from 

 plates made when the same specimen of 

 faeces had been kept for 126 days. Growth 

 was slower than usual, but the colonies 

 finally presented the irregular outline, the 

 translucent border and relief-map surface- 

 markings which characterize the colon 

 bacillus. The branching appearance of the 

 stroke cultures on gelatine did not appear 

 for several days. Growth on agar-agar 



was typical and the faecal odor distinct. 

 Milk was not coagulated by these cultures, 

 even when it was boiled. The indol-reac- 

 tion was distinct in every case. A micro- 

 scopical examination showed a short, motile 

 bacillus in pairs, or sometimes in chains of 

 two or three, which in very young cultures 

 might be mistaken for cocci in the stained 

 specimens; but in the hanging drop the 

 shape was easily seen and the motility was 

 nearly as great as that of the typical colon 

 bacillus. The fermenting function was 

 entirely lost with all the sugars used. An 

 acid reaction in every tube showed that 

 the sugars were broken up into acids, to 

 some extent. 



These cultures, which after careful study 

 are considered as true colon bacilli attenu- 

 ated by prolonged dwelling in undiluted 

 faeces, correspond very closely to those de- 

 scribed by Yillinger^" in his investigations 

 upon the changes produced in the colon 

 bacillus by environment. A tested culture 

 of the colon bacillus was so changed by dif- 

 ferent chemical and physical influences that 

 nearly all of the characteristics by which it 

 is differentiated from other organisms were 

 lost. Some of these functions could be again 

 revived by repeated changes in a favorable 

 medium. The indol-formation, however, 

 was never regained. 



An attempt was mad© to attenuate a 

 tested culture of the colon bacillus by 

 inoculating it into diluted, sterilized, ty- 

 phoid faeces. It was put into this me- 

 dium on December 20, 1895, where it 



