ZOOLOGY AND BOTANY, MIOEOSCOPY, ETC. 825 



procedure 30 different kinds of bacteria were bred, which developed 

 between 56° and 58°. With higher and lower temperatures different 

 kinds of bacteria appeared. At 68°-70°5 only a few colonies developed, 

 while if the temperature were lowered to 50° or below, the potato 

 bacillus appeared, and this overgrew all other colonies. The author notes 

 that these bacilli are located on the superficial layers of the mould, and 

 that the sun's warmth must be the most powerful factor in their genesis. 



Alkali- Albuminate as a Nutrient Medium.* — Prof. J. Rosenthal 

 and Dr. 0. Schulz make alkali-albuminate in the following manner 

 which is simpler than that of Tarchanoff. 



The albumen taken from fresh hens' eggs is separated from the 

 chalazse, and clarified before it is mixed with the alkali solution. This 

 is done in the most simple way by straining the albumen through a bag 

 made of a double layer of muslin. It should be squeezed through 

 slowly with the hand. The filtrate, quite clean and free from bubbles, 

 is then poured into a gi-aduated vessel closed with a ground-glass stopper 

 and diluted with a 1 per cent, solution of caustic soda or potash and 

 distilled water. The proportions are, to every 5 com. albumen, 3 ccm. 

 alkali solution, and 2 ccm. water. The mixture is then shaken until it 

 froths, after which it is allowed to stand for some hours, when the 

 shaking is repeated in order that the three constituents may be inti- 

 mately mixed. The alkali-albuminate is then poured into test-tubes, 

 Erlenmayer's bulbs, or flat glass pans, and heated over water to a tempera- 

 ture of 95°-98° C. for a short time. In a few minutes a jelly is pro- 

 duced, which in thin layers is perfectly clear, in thick somewhat opal- 

 escent, but which always possesses the consistence and transparency 

 requisite for a nutrient medium. Heating up to 100° C. should be 

 avoided, as bubbles are produced owing to the vaporization of the water. 



The alkali-albuminate may, if desired, be modified by the addition of 

 certain inorganic salts (NaCl, KCl, Na^COg, Na^SOi, NaHPO^, &c.), or 

 by diluting with other nutrient fluids ; thus the authors have obtained 

 very good results from the following mixture : — 5 ccm. albumen and 

 2 • 2 ccm. 1 per cent, alkali solution mixed with meat infusion, diluted 

 about one-half with distilled water so that the whole quantity amounted 

 to 10 ccm. 



Preparation of Nutrient Gelatin and Agar.f — The practical worker 

 in bacteriology deplores, says Dr. T. L. Cheesman, jun., the loss of 

 time usually attendant upon the preparation, and especially upon the 

 filtration of nutrient gelatin and agar. The method formulated by Koch 

 and closely followed by most workers, is very satisfactory in producing 

 good, clear culture media, but a few modifications render the procedure 

 a much less formidable one, and as the changes to be suggested are 

 simply those of detail, it may be well to state in brief the method now 

 in use in the Bacterial Laboratory of the College of Physicians and 

 Surgeons, New York, which after considerable trial gives uniform and 

 satisfactory results. One pound of finely chopped beef, as free as possible 

 from fat and gristle, is mixed with 1000 ccm. of distilled water and kept in 

 a cool place for 12 or 18 hours. It is then strained, cold, through a 

 coarse cloth, into a wide-mouthed " agate ware " or " enamelled iron " 

 vessel of sufficient size, and 5 gm. of C.P. sodium chloride, 10 gm. of 



* Biol. Centralbl., viii. (1888) pp. 307-11. 

 t Amer. Naturalist, xxii. (1888) pp. 472-3. 



