210 THE AMERICAN MONTHLY. [September, 



TECHNIQUE. 



Method for Fixing Preparations Treated by Sublimate or 

 Silver (Golgi's Method.) — Sig. A. Obregia gives a method for ren- 

 dering preparations treated by Golgi's sublimate or silver procedure so 

 permanent that they may be afterw^ards stained and protected with a 

 cover-glass. 



The sublimate or silver preparations are sectioned without any imbed- 

 ding or after having been imbedded in paraffin or celloidin. In the 

 latter case care must be taken not to use alcohol weaker than 94 or 95 

 per cent, at any rate for the silver preparations. The sections are then 

 transferred from absolute alcohol to the following mixture : i per cent, 

 gold chloride solution, S-io drops; absolute alcohol, 10 ccm., which 

 should have been made half an hour previously and exposed to diffuse 

 light. After the sections are deposited therein the vessel containing 

 them is placed in the dark. The silver is gradually replaced by gold, 

 and the mercury changed into gold amalgam. Finally, black delicate 

 designs appear on a white field. According to the thickness of the 

 section, the fluid is allowed to act from 15 to 30 minutes, but even longer 

 is not harmful. Thereupon the sections are quickly washed first in 50 

 per cent, alcohol, then in distilled water, and finally in a 10 per cent, 

 solution of hyposulphite of soda, in which, according to their thickness, 

 they remain from 5 to 10 minutes. A longer immersion bleaches too 

 much, so that the finer fibres disappear. Last of all they are thoroughly 

 washed in distilled water twice renewed. 



Sections thus fixed can afterwards be stained by any method — c.^., 

 Weigert's, Pal's, etc. — after which they are cleared up with creosote, 

 imbedded in damar, and protected with a cover of glass. 



Throughout the procedure the sections must be manipulated with 

 glass instruments, and not allowed to touch any metallic substance. — 

 Virchow' s Archiv.^ cxxil (i8go.) 



New Method of Injecting Fluids into the Peritoneal Cavity 

 of Animals. — In the issue of the British Medical yournal for June 

 6, 1891, Dr. A. F. Stevenson and Dr. D. Bruce describe a method for 

 injecting fluids into the peritoneal cavity without danger of wounding 

 the intestines with the point of the hypodermic needle. The needle is 

 curved, its anterior half being solid, while the posterior part is hollow, 

 the opening being in the middle, i. e., at the junction of the two halves. 

 It may be fitted to any syringe. When using it, the abdominal wall of 

 the animal is pinched up v\ ith thumb and forefinger of two hands, and 

 then the needle plunged through until the middle (the opening) is in 

 centre of the pinched-up tissue. Hence, when the skin is relaxed the 

 opening of the needle is freely within the peritoneal cavity. 



Three Useful Staining Solutions. — Dr. R. Haug gives in 

 Zeitschr. f. Wiss. Mikr., viii {j8gi)^ the three following formulas for 

 staining solutions which are stated to be extremely effective : 



Haamatoxylin in acetic acid-alum, i grm. of haematoxylin is dissolved 

 in 10 ccm. of absolute alcohol, and this mixed wnth 200 ccm. of liquor 

 aluminis acetici (German PharmacopaMa — see also " Extra Pharmaco- 

 pceia). The fluid, at first violet-black, becomes brownish-black in the 

 course of a few weeks, and its maturation may be hastened by the addi- 



