JDecember 11, 1914] 



SCIENCE 



863 



Work on this whole apparatus and its prod- 

 ucts is being pursued by Mr. C. C. Speidel 

 and the writer to determine its structure and 

 function, which is supposed to have some rela- 

 tion to the electric apparatus of the skates, 

 ■■■even if it does not prove to be the motor nerve 

 ■cells of this apparatus. 



TJlric Dahlgren 



the effect of storage in river water (steril- 

 ized) on the production of acid in 

 carbohydrate solutions by the 

 bacillus coli group 

 During the last decade, the fermentation of 

 the various carbohydrates with the production 

 of acid and gas has been used almost exclu- 

 sively for dividing the Bacillus coli group 

 into many subdivisions. Theobald Smith 

 (1893) seems to have been the pioneer in this 

 field by his division of the colon group by the 

 -use of saccharose. Of the later workers, Win- 

 slow and Walker (1907) and MacConkey 

 (1905) seem to have done the most careful 

 -work. MacConkey divided the Bacillus coli 

 group into four subgroups by the use of dulcite 

 and saccharose according to the following 

 •scheme : 



Saccharo.'-e Dtilciie 

 B. coli communis . . — + 



B. coli communior . . + -|- 



B. coli aerogenes . . . + — 



B. coli acidi lactici. — — 



In 1909 MacConkey further subdivided the 

 ;groups by the addition of motility and lique- 

 :faction of gelatine to his tests. Jackson (1911) 

 in America subdivided MacConkey's original 

 scheme by the use of mannite, raffinose, ni- 

 trate reduction, indol production, motility 

 and other similar reactions. The fermenta- 

 tion of carbohydrates certainly offers a fruit- 

 ful field for the classification of the Bacillus 

 ■coli group, but we must soon decide just what 

 the limits of fermentation must be, for the list 

 of carbohydrates now in use is a long one and 

 increasing steadily. The question will soon 

 come to the front, " Are these fermentations 

 ■of the various carbohydrates permanent func- 

 tions of the organisms ? " Horroeks (1903) 

 :£ound that members of the Bacillus coli group 



wliich were kept in sterilized sewage and 

 Thames River water as well as in well water 

 showed only a weak production of indol and 

 a delayed action on milk. Peckham (1897) 

 also found that the production of indol is vari- 

 able. The purpose of the present work was 

 to determine the permanency of acid production 

 in carbohydrate solutions by the Bacillus coli 

 group in stored river water. Three organisms 

 of the original MacConkey scheme were used, 

 namely, B. coli communis, acidi lactici, aero- 

 genes. 



Procedure 



Water was taken from the Hudson Eiver 

 near the outlets of a sewer and 100 c.c. was 

 poured into 30 bottles of 250 c.c. capacity. 

 The water was sterilized and the sterilization 

 tested by plating out respective samples. 

 Pure agar cultures of B. coli communis, aero- 

 genes, acidi lactici were emulsified in^ steril- 

 ized water. One cubic centimeter of this 

 emulsion was placed in each bottle thus giving 

 ten bottles of communis, acidi lactici and 

 aerogenes. These bottles were stored away in 

 a dark closet at 20° C. At various intervals 

 inoculations were made into the carbohydrate 

 solutions and titrations made at the end of the 

 twenty-fourth hour or as near as possible to 

 that period. During the course of the experi- 

 ment the following carbohydrates were used: 

 Dextrose, lactose, raffinose, saccharose, salicin, 

 maltose and mannite. 



The carbohydrates and other media used 

 during the work were made according to stand- 

 ard methods of water analysis, report of 1905. 

 Liebig's Meat Extract (3 grams to the liter) 

 was used in place of meat and gave entirely 

 satisfactory results. The method used in 

 titrating the cultures followed standard meth- 

 ods in detail. Five cubic centimeters of the 

 carbohydrate solution to be tested and 45 cubic 

 centimeters of distilled water were placed in 

 a casserole and boiled briskly for 1 minute. 

 One cubic centimeter of phenolphthalein was 

 added as indicator, and titration was made into 

 the hot solution with N/20 NaOH. All re- 

 sults are expressed in per cent, normal. All 

 cultures were incubated at 37° C. and titrated 

 at the twenty-fourth hour. Controls were run 



