498 SUMMARY OF CURRENT RESEARCHES RELATING TO 



cover the lower end of B. The oxygen is completely absorbed in from 

 1£ to 2 hours. When the cultivation is finished and it is required to 

 take out the tube, the mercury must be poured off before the cap is 

 removed. 



Method for examining Nutrient Media.* — S. Weissbein examined 

 ten different substances with nutrient properties (plasmon, galactogeu, 

 Heyden's medium, and others) by the aid of Pappenheim's panoptic tri- 

 acid solution. Some of the powdered medium was mixed with distilled 

 water, to which ten drops of the staining solution were added. This 

 mixture was then centrifuged for about two minutes and then the stained 

 sediment was examined under the Microscope. To estimate the amount 

 of starch, about two drops of tincture of iodine were added to the sedi- 

 ment, and this again centrifuged. Owing to the selective action of the 

 components and constituenta of the media, different stainings of the 

 powdered substances were obtained. As the different colourings indicate 

 different chemical constitution, the method adopted gives much infor- 

 mation as to the nature of a nutrient substance and its value as an 

 artificial medium. 



(2) Preparing Objects. 



Simple Method of Fixing Bacteria to the Slide or Cover-Slip 

 without Drying.f — G. von Wendt takes a loopful of a bacterial culture 

 and mixes it with a drop of water in a watch-glass. If desired, the 

 bacteria may be fixed by using 1-3 p.c. nitric acid or ^-3 p.c. sublimate, 

 &c. instead of pure water. A very thin layer of Meyer's albumen- 

 glycerin is smeared on slides or slips, and the films moistened with a 

 few drops of water. A loopful of the bacterial suspension is then de- 

 posited in the water lying on the films. The slide or slip is then 

 covered with a sufficiently large watch-glass. In 20-30 minutes the 

 bacteria will have settled down, and then the covering watch-glass is 

 removed to allow a few drops of water to be deposited on the film. 

 The watch-glass is then replaced, and the whole is placed in an in- 

 cubator at 75° for 8-10 minutes. In this way the albumen is coagulated 

 and the bacteria fixed to the slide or slip. The watch-glass must fit 

 tight over the slide to prevent evaporation, and must not be removed 

 until the preparation is cooled down sufficiently, after which the films 

 may be stained, passed through graded alcohols, and mounted in balsam. 



(3) Cutting-, including- Imbedding- and Microtomes. 



Simple Method for Making Bone Sections.^ — J. P. Burkholder cuts 

 transverse slices of bone 2-3 mm. thick with a fine saw. One surface 

 is polished on a dry whetstone and then gummed on to a smooth piece 

 of wood 1 by 1 by 2 cm. in size. When thoroughly dry most of the 

 slice may be sawn off, and the rest rubbed down on the wetted whetstone 

 until it is so thin that the grain of the wood can be clearly seen through 

 it. By the aid of a little hot water the bone is easily separated from 

 the wood block. Then place the section on the wetted whetstone and 



* Deutsch. Med. Wochenschr., xxviii. (1902) pp. 24-6. 

 t Centralbl. Bakt. Orig., 1" Abt., xxxi. (1902) pp. 671-2. 

 X Journ. App. Micr., v. (1902) p. 1781. 



