LABORATORY AND GREENHOUSE STUDIES. 



75 



Summary of starch-media experiments. — The result h of tlic.se experi- 

 ments may be briefly summarized as follows: 



Experiment 1 

 2 

 3 



Potato cylinders, amylodextrin formed. 



Peptone-dextrose cornstarch solution, amylodextrin formed. 



Peptone-potato starch solution, amylodextrin formed. 



Peptone-dextrose potato-starch solution, no amylodextrin formed. 



Peptone-potato starch with litmus, no acid formed; not tested for 

 amylodextrin. 

 4 a. Starch jelly, no amylodextrin. 

 4 b. Starch jelly, amylodextrin formed. 

 4 c. Starch jelly, amylodextrin formed. 

 4 d. Starch jelly, no amylodextrin formed. 



These experiments demonstrate the ability of the coconut organism 

 as well as Bacillus coli to change starch into amylodextrin, although 

 this power appears to be variable. Bacillus coli is, in general, more con- 

 stant in this power and usually more effective. Contrary to the fore- 

 going results of the author in regard to Bacillus coli, Savage * states 

 that true Bacillus coli does not ferment starch. 



PRODUCTION OF ACID AND GAS IN GLYCERIN.^ 



Cultures in peptone plus glycerin after growth for 5 days titrated 

 + 10 for cultures of coconut No. 3 and -f 11 for coconut No. 4. The 

 gas production in this medium is shown in tlie following table : 



Table X. — Amount of gas (in mm.) produced in 1 per cent peptone plus 1 per cent 



glycerin at 22° C, February 4 to 20., 1910. 



In Table X it is seen that cultures Nos. 2 and 5 have produced gas 

 in the glycerin medium while the others have failed. This experi- 

 ment was repeated to determine if the same result would again be 

 obtained at a higher temperature. The results appear in Table XI, 



1 Savage. W. G. The Characters of the Bacillus Coli as an Indicator of Excretal Contamination. 

 Lancet, London, vol. 108, Feb. 4, 1905, p. 287. 



2 Giddings, N. J. A Bacterial Soft Rot of Muskmelon, Caused by Bacillus Melonis, n. sp. Bulletin 148, 

 Vermont Agricultural Experiment Station, January, 1910, p. 400. The author reports 6 per cent of gas 

 formed in nutrient broth cultures of Bacillus coli containing 2 per cent glycerin. 



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