LABORATORY AND GREENHOUSE STUDIES. 121 



remy's synthetic medium.' 



Remy uses an artificial nicdiuin approximating a potato in com- 

 position, but without dextrin or glucose. The composition is as 

 follows : 



Composition of Remy^s synthetic medium. 



Grams. 



Distilled water 1, 000. 



Asparagin 6. 



Oxalic acid .5 



Lactic acid .15 



Citric acid .15 



Disodic phosphate 5. 



Magnesium sulphate 2. 5 



Potassium sulphate 1. 25 



Sodium chlorid 2. 00 



All the salts excepting the magnesium sulphate are powdered in a 

 mortar and introduced into a flask with the distilled water. Thirty 

 grams of Witte's peptone are then added and the mixture heated 

 in the autoclave under pressure for 15 minutes. As soon as removed 

 the contents are poured into another flask into which 120 to 150 

 grams of gelatin have previously been placed. The flask is shaken 

 to dissolve the gelatin, and the contents are then made slightly alka- 

 line with soda solution. The mixture is again heated in the autoclave 

 at 110° C. for 15 minutes, then acidified with a one-half normal solu- 

 tion of sulphuric acid, so that 10 c. c. have an acidity neutralized by 

 0.2 c. c. of one-half normal soda solution. This acidity is equal to 

 0.5 c. c. sulphuric acid per liter. After shaking the flask is placed 

 in a steam sterilizer for 10 minutes, then the solution is filtered, 

 and the acidity of the medium verified and corrected if necessary. 

 Finally the magnesium sulphate is added, dissolved, after which the 

 medium is tubed and sterilized by the intermittent method. 



At the moment of using, 1 c. c. of a 35 per cent solution of lactose 

 and 0.1 c. c. of a 2.5 per cent solution of carbolic acid are put into 

 each tube. 



Upon this medium the Bacillus coli colonies are said to be yellowish 

 brown, the typhoid colonies bluish white and small. Fine bubbles of 

 gas from the fermentation of the lactose often occur about the Bacillus 

 coli. 



Plates with Remy's medium, April 14 to 18. 



Two days: No. 4, densely occupied by tiny white colonies. The other coconut 



plates and Bacillus coli just the same. 

 Three days: Plates just the same as two days. 

 Four days: Coconut and Bacillus coli. The colonies are very numerous on each 



plate. Where the medium is fairly thick they appear white, and where it is 



1 Remy, L. Contribution h, I'fetude de la Fifevre Typhoide et de Son Bacille. Annales de I'lnstitut 

 Pasteur, Paris, vol. 14, Augiast, 1900, pp. 555-570. 



228 



