ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



109 



composition for isolating B. typhosus from stools, etc. : 3 p.c. agar, 

 1 p.c. gelatin, 3 p.c. peptone, 3 p.c. lactose, 0*7-1 p.c. taurocholate. 

 The taurocholate is prepared from ox-bile by precipitating with alum, 

 and then treating the filtrate with perchloride of iron. The resulting 

 fluid is filtered until quite clear. This filtrate, which is strongly acid, 

 is neutralised with sodium carbonate, and after addition of some animal 

 charcoal, is evaporated on a water-bath. The residue is treated with 

 alcohol and filtered, the treatment being repeated twice, and then the 

 dry residue dissolved in water to make a 10 p.c. solution, after which it 

 is sterilised at 110° C. 



Simple Thermostat.* — A. Sineff describes an effective incubator 

 which any person can make. It is made of cardboard or a thin wood 

 used for box-making. It has a lid 

 through which a thermometer is in- 

 inserted (fig. 23), and at its lower 

 part, just above the bottom, a 

 couple of slits for the insertion of 

 an iron plate. Convenient sizes are 

 20 x 20 x 20 cm. or 30 x 20 x 20 

 cm., the iron plate being 18 x 50 cm. 



As shown in the illustration, the 

 iron plate is heated by means of a 

 paraffin lamp or other source of 

 heat, after the manner of the early 

 hot-stage. The apparatus is said to 

 be capable of working within ■ 5°. 



Sterilised Bacterial Media for 

 Cultivation of Anaerobes. f — GL 

 Proca finds that used and sterilised 

 cultures of certain bacteria form 



excellent media for cultivating anaerobes in the presence of air. The 

 tubes should be sterilised at 65-70° C, and inoculated directly they have 

 cooled sufficiently. In broth the growth is scanty, but more abundant 

 cultures are obtainable by pouring the inoculated medium over agar or 

 serum slopes. Instead of cultures, thick suspensions of bacteria may be 

 used, and agar tubes be liquefied, and, after inoculation, be rapidly 

 cooled down. Good growth takes place in the depth of the medium 

 provided the surface be covered with a broth culture sterilised at from 

 65-70° C. The cultures used were those of B. coli, B. typhosus, and 

 Vibrio cholera, and the anaerobes cultivated were B. tetani, B. botulinus, 

 a club-shaped bacillus isolated from earth, and a bacillus obtained from 

 a case of gangrene. 



Observing Living Developing Nerve-fibres. J — The method em- 

 ployed by R. G. Harrison was to isolate pieces of embryonic tissue 

 known to give rise to nerve-fibres, such as the whole or fragments of 

 the medullary tube or ectoderm from the branchial region, and to 

 observe their further development. The pieces were taken from frog 



* Centralbl. Bakt., lte Abt. Orig., xlv. (1907) pp. 191-2 (1 fig.). 

 t C.B,. Soc. Biol. Paris, lxiii. (1907) pp. 620-1. 

 % Amer. Journ. Anat., vii. (1907) pp. 116-18. 



Fig. 23. 



