ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 259 



colonies. If the medium be stained with the author's indigo-fuchsin 

 solution, the typhoid bacilli change the blue to red, while the coli bacilli 

 decolorise the substratum. 



For making the decoction poisonous or edible mushrooms may be 

 used. 



New Method for Cultivating Tubercle Bacillus.* — Dr. W. Hesse de- 

 scribes a nutrient medium which is made by dissolving 5 grm. Heyden's 

 nutriment, 5 grm. salt, 30 grm. glycerin, and 10 grm. agar, in 1000 ccm. 

 water, and alkalised by the addition of 5 ccm. mineral soda solution. 

 Plates are made in Petri's capsules, and tubercle bacilli grown thereon 

 from direct inoculation with sputum. On this medium tubercle bacilli 

 almost invariably grow, and in the exceptional cases where the culture 

 is overgrown by other bacteria, impression preparations invariably dis- 

 close their preseuce. The author believes that this method will supersede 

 the animal test in many doubtful cases. 



Cultivating Water Bacteria in an Atmosphere Saturated with. 

 Moisture. f — Mr. G. C. Whipple has shewn, by a series of experiments, 

 that in order to obtain the greatest possible development of water 

 bacteria on the gelatin-plate, a ventilated dish should be used, and the 

 cultures should be incubated in an atmosphere saturated with moisture. 

 The observations were made on cultures placed in (1) moist chamber, 

 (2) ice-chest, (3) incubator, (4) closed chamber, and (5) desiccator. The 

 largest number of bacteria were always obtained from plates developed 

 in the moist chamber, and the least from those in the desiccator. It was 

 also found that there was a direct relation between the humidity and the 

 number of bacteria developed, and that the supply of oxygen had a 

 marked effect on the growth of the water bacteria on the gelatin plate. 

 The practical outcome of these observations was that satisfactory results 

 were obtained by making small notches on the lower edge of the Petri 

 plate, or by extending the sides of the lower plate upwaids at four points 

 so as to allow of free circulation of air. These ventilated dishes, placed 

 in an atmosphere saturated with moisture, were not only successful, but 

 were perfectly free from danger of contamination. Cultivation in a moist 

 atmosphere has the further advantage of bringing the bacterial growth 

 to maturity in a shorter time. The incubators should be well ventilated, 

 and their atmosphere kept at or near saturation point. They should be 

 provided with dry and wet bulb thermometers, and the relative humidity 

 should not he allowed to fall below 95 per cent. 



Cultivating and Demonstrating the Micro-organisms from Tumours. t 

 — Dr. Nils Sjobring has motivated the microbes of cancer in a medium 

 composed of ordinary pepton-gelatin (8 per cent.) and strong aqueous 

 solution of potash-soap made with human fat (1*5 per cent.). To this 

 1 per cent, cane or grape-sugar is added, and then the mixture is steri- 

 lised. Usually 50 per cent, sterile ascitic fluid was added, but this is 

 not an absolute necessity. The amount of free alkali should be much 

 greater than in bacterial substrata ; even 2 per mil. is not unfavour- 

 able. Pieces of tumour freshly excised were placed in the tubes and 



* Zeitscbr f. Hygiene, xxxi. p. 502. See Centralbl. Bakt. u. Par., l u Abt., 

 xxvii. (1900) p. 119. t Technology Quarterly, xii. (1899) pp. 276-82. 



J Centralbl. Bakt. n. Par., 1'" Abt, xxvii. (1900) pp. 129-40 (4 figs.). 



