G58 SUMMARY OF CURRENT RESEARCHES RELATING TO 



burette is then immediately immcrsccl in the hot solution, fillotl with it, 

 and placed in connection with the bulb A ; and the nutrient solution 

 in A is then further sterilized by long boiling. After the sterilized 

 nutrient sohition has becf)me cold, it is neutralized from the burette until 

 the red colour has almost entirely disappeared ; and the germs arc then 

 introduced into A through the lower neck. The exchange of gases 

 between the interior of the apparatus and the external air can take placo 

 only through this neck, which is stopped by a wad. In experiments 

 where quantitative estimation is required, the burette B may be replaced 

 by another, represented at the right of fig. 108. 



PiTEREN, M. D. V. — TJeber Bereitung fester Nahrungsgemische fur Mikroben ans 

 der Milch. (On the preparation of solid nutrient media for microbes from milk.) 



Wratsch, 1888, pp. 281-4 (Russian). 



(2) Preparing' Objects. 



Preservation of Parts and Organs of Animals.* — Dr. A. Misch- 

 told praises highly Giacomiui's method of preserving organs, both 

 normal and pathological. The parts retain their normal size and ap- 

 pearance and remain perfectly supple, so that they can be placed in any 

 position. 



With time the volume diminishes about 1/20, but the weight is in- 

 creased by 150-200 grm. in consequence of the impregnation. The 

 procedure is as follows : — The organ, for example a whole brain, is first 

 of all injected through an artery with a saturated filtered solution of 

 chloride of zinc, and then placed in a solution of this until the brain 

 has sunk down to the bottom of the vessel. 



During this time (about eight days) it is advisable to strip ofif the 

 membranes, otherwise rusty patches appear along the course of the 

 vessels. The brain is then placed in strong spirit for ten or twelve 

 days, or until it has sunk to the bottom. The spirit must be changed 

 two or three times. It is next placed in pure glycerin, to which 1 per 

 cent, of carbolic acid is added, until it again sinks to the bottom. The 

 preparation should be turned over several times, and when saturated 

 with glycerin should be exposed to the air for several days upon a layer 

 of cotton-wool to dry. It is finally coated over with a thin layer of 

 a solution of gummi elasticum or guttapercha in benzin. For prepara- 

 tions other than brains an 8 per cent, zinc chloride solution is advised, 

 and for still smaller ones a solution half as strong. 



Two new Methods for preparing Nerve-cells.f — (1) Instantaneous 

 preparation. — Prof. L. v. Thanhoffer takes a small piece from the grey 

 substance and presses it between tw'O cover-glasses, so that when drawn 

 apart there adheres to both a thin layer of nervous matter. The cover- 

 glass is then heated in the flame of a spirit-lamp or of a gas-jet until the 

 nervous layer has assumed a blackish-brown colour, and a distinct smell 

 of burning is perceptible. The preparation is then mounted in xylol- 

 dammar. The nerve-cells and the nuclei of the neuroglia-cells, as well 

 as the blood-vessels and their nuclei, are very clearly seen in such pre- 

 parations. 



(2) Double cover-glass preparation. — To produce jiermanent and 



» Morskoi Sbornik, Supplement, 188G, pp. 207-9. Cf. Zeitsclir. f. Wiss. Mikr., 

 iv. (18M7) p)). 37.5-6 



» Zeitschr f. Wiss, Mikr., iv. (1SS7) i^) tr,7-'.t. 



