Potatoes 199 



is distributed in tubes, and sterilized and coagulated like the blood- 

 serum itself. As prepared by Lofiler it was soft, semi-gelatinous 

 and semi-transparent, not firm and white; therefore should be steril- 

 ized at low temperatures. Many organisms grow more luxuriantly 

 upon it than upon, either plain blood-serum or other culture media. 

 Its especial usefulness is for the cultivation of Bacillus diphtherise, 

 which grows rapidly and with a characteristic appearance. 



Alkaline Blood-serum. — According to Lorrain Smith, a very useful culture 

 medium can be prepared as follows: To each 100 cc. of blood-serum add i-i.S 

 CO. of a 10 per cent, solution of sodium hydrate and shake it gently. Put suffi- 

 cient of the mixture into each of a series of test-tubes, and, laying them upon 

 their sides, sterilize like blood-serum, taking care that their contents are not 

 heated too quickly, as then bubbles are apt to form. The result should be clear, 

 solid medium consisting chiefly of alkali-albumins. It is especially useful for 

 Bacillus diphtherias. 



Deycke'sAlkali-albuminate. — One thousand grams of meat are macerated for 

 twenty-four hours with 1200 cc. of a 3 per cent, solution of potassium hydrate. 

 The clear brown fluid is filtered off and pure hydrochloric acid carefully added 

 while a precipitate forms. The precipitated albuminate is collected upon a cloth 

 filter, mixed with a small quantity of liquid, and made distinctly alkaline. To 

 make solutions of definite strength it can be dried, pulverized, and redissolved. 



The most useful formula used by Deycke was a 2.5 per cent, solution of the 

 alkali-albuminate with the addition of i per cent, of peptone, i per cent, of 

 NaCl, and gelatin or agar-agar enough to make it solid. 



Potatoes. — Without taking time to review the old method of 

 boiling potatoes, opening them with sterile knives, and protecting 

 them in the moist chamber, or the much more easily conducted 

 method of Esmarch in which the shoes of potato are sterilized in the 

 small dishes in which they are afterward kept and used, we will at 

 once pass to what seems the most simple and satisfactory method — 

 that of Bolton and Globig.* 



With the aid of a cork-borer or Ravenel potato cutter a little 

 smaller in diameter than the test-tube ordinarily used, a number 

 of cylinders are cut from potatoes. Rather large potatoes should 

 be used, the cyUnders being cut transversely, so that a number, 

 each about an inch and a half in length, can be cut from one potato. 

 The skin is removed from the cyHnders by cutting off the ends, after 

 which each cyhnder is cut in two by an oblique incision, so as to 

 leave a broad, flat surface. The half-cylinders are placed each in a 

 test-tube previously steriUzed, and are exposed three times, for half 

 an hour each, to the streaming steam of the sterilizer. This steam- 

 ing cooks the potato and also sterilizes it. Such potato cylinders are 

 apt to deteriorate rapidly, first by turning very dark, second by 

 drying so as to be useless. Abbott has shown that if the cut cyHn- 

 ders be allowed to stand for twelve hours in running water before be- 

 ing dispensed in the tubes, they are not so apt to turn dark. Drying 

 may also be prevented by adding a few drops of clean water to each 

 tube before sterilizing. Some workers insert a bit of glass or a 

 pledget of glass wool into the bottom of the tube so as to support 

 *."The Medical News," 1887. vol. 1. d. i;?8. 



