816 



CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



(2) Remove all the eyes and any suspi- 

 cious spots. 



(3) Soak in 1 : 1000 solution of bichloride 

 of mercury for an hour. 



(4) Steam at 100°C. for one hour. 



(5) Do not remove from the sterilizer 

 but steam for 15 minutes on the 

 second and third days. 



(6) Divide the potatoes in halves by 

 means of a sterilized knife, and 

 place in a sterilized container 

 (Petri dish) with the cut surfaces 

 uppermost. Do this under aseptic 

 conditions. 



(b) A number of different investigators 

 prepared potatoes in a very similar 

 manner. The individual differences 

 were not large enough to warrant a 

 discussion of each method. 

 References: Wurtz (1897 p. 31), Smith 



(1902 p. 74), Abel (1912 p. 27), Tausz 



and Peter (1919 p. 49), Klimmer (1923 



p. 204). 



2494. Wurtz 's Potato Slants 



Constituents : 



1. Potato. 

 Preparation : 



(1) Cut well washed potatoes in rec- 

 tangular prisms 5 cm. long. 



(2) Place in Roux tubes. 

 Sterilization: Sterilize at 120° for 30 



minutes. 

 Use: General culture medium. 

 Variants : 



(a) Thoinot and Masselin prepared the 

 potatoes as follows: 



(1) Cut clean potatoes into rectangular 

 pieces or prepare cylindrical pieces 

 by use of a cork borer. 



(2) Split the cylinders giving semi- 

 cylinders. 



(3) Wash the pieces of potato carefully 

 with water and dry between filter 

 paper. 



(4) Place each piece in a Roux tube. 



(5) Sterilize in the autoclave at 115° 

 for 30 minutes, or at 120° for 20 

 minutes. 



(b) Smith prepared the medium as 

 follows: 

 (1) Wash large sound potatoes in run- 

 ning water using a stiff brush. 



(2) Remove all the eyes and any suspi- 

 cious spots. 



(3) Cut the ends from the potatoes and 

 cut cylindrical pieces, using a cork 

 borer. 



(4) Cut the cylinders obliquely so that 

 each resulting piece presents a 

 round flat end and a large oval 

 beveled surface. 



(5) Place the pieces in running water 

 for several hours or over night if 

 convenient. 



(6) Place one piece of potato into 

 sterile tubes containing a bit of 

 glass rod. The beveled side of the 

 potato should be up. 



(7) Sterilize by heating at 100°C. for 

 30 minutes on one day and for 

 15 minutes on the second and third 

 successive days, or in the autoclave 

 at 120°C. or 30 to 40 minutes. 



(8) The potatoes may be cut in discs, 

 placed in Petri dishes and then 

 sterilized. 



(c) Roddy used the following method to 

 prepare potatoes: 



(1) Wash a smooth new potato in hot 

 water, hot 1:500 bichloride and then 

 in several changes of hot water. 



(2) Cut cylindrical pieces about 1.5 

 inches long and about the same 

 diameter of the tubes in which they 

 are to be placed. 



(3) Split each cylinder diagonally in 

 two thru the long axis. 



(4) Place each piece in a tube, with the 

 thick end at the bottom. 



(5) Add about 0.25 inch of distilled 

 water. 



(6) Sterilize in the autoclave. 



(d) Harvey gave the following method of 

 preparation: 

 (!) Wash and scrub the potato thoroly. 



(2) Peel and remove eyes. 



(3) Prepare cylinders by means of an 

 apple corer or a large cork borer. 



(4) Divide the cylinder diagonally in 

 two parts. 



(5) Soak for not more than 24 hours in 

 1-1000 sodium carbonate. 



(6) Place on top of sterilized cotton 

 wool moistened with sterile water 

 in the bottom of a tube. 



(7) Sterilize. 



