808 SUMMARY OF CURRENT RESEARCHES RELATING TO 



quantity of alum crystals fall down, it is advisablo to decant the solu- 

 tion and preserve in another bottle. 



According to the author, this carmine stains microscopical sections 

 in a few minutes, and the nuclei stand out quite conspicuously against 

 the prettily stained protoplasm. It may also he used for staining en 

 masse preparations for paraffin imbedding. Staining en bloc usually 

 takes from 12 to 24 hours, although the size of the preparation and 

 its histological construction modify these limits considerably. This 

 carmine is said to possess the advantage of keeping for a long time 

 "without growing mouldy. 



Weigert's Hematoxylin Stain.* — Dr. M. Flcsch, with the co- 

 operation of Dr. Berliner Blau, has succeeded in reducing the expense 

 of the Wcigert process by regenerating the once used staining solu- 

 tion. This is effected by adding 5 to 10 cm. baryta water to about 

 200 c.cm. of the used solution. The mixture having been shaken up 

 several times is allowed to stand for 24 hours. Carbonic acid gas, 

 made with hydrochloric acid and marble, is then passed through and 

 after 24 hours is filtered. Stainings obtained from this filtered solu- 

 tion cannot be distinguished from those obtained with the original. 

 An attempt was made to recover the pure dye, but this quite failed. 



With regard to the copper modification,'!' the author now lays the 

 separate sections on cellulose paper, whereon they are placed in the 

 copper solution ; from this they are transferred to a 70 per cent, 

 spirit, and thence to the stain. 



Dr. Flesch gives the preference to the copper acetate solution over 

 his own chromic acid modification J for fine nerve-fibres, but for 

 nerve-cells, especially in peripheral ganglia, he has entirely given up 

 the copper for chromic acid solution. The medulla of central and 

 peripheral nerves is also much better demonstrated by the latter solu- 

 tion. Where deep staining is required he advises the use of the incu- 

 bator, and instead of ordinary watchglasses, nests of glasses will be 

 found more handy. For clearing up, he continues to find kreasote to 

 possess advantages over other clarifiers. 



Staining in toto the Central Nervous System with Weigert's 

 Hsematoxylin.§ — Dr. C. E. Beever first hardens the preparation in 

 methylated spirit, and then for one to four weeks in 3 per cent, 

 potassium bichromate. He then changes to methylated spirit again, 

 for one or two days, and next treats with haematoxylin for four days, 

 raising the temperature every day for three or four hours to 40°- 

 50° C. The haematoxylin solution was twice as strong as that used 

 by Weigert (200 parts absolute alcohol, 2 parts hematoxylin, and 130 

 parts water). The pieces, having been washed, were transferred to a 

 solution of potassium ferridcyanide, 2 ' 5 parts ; borax, 2 parts ; water, 

 100 parts. The solution was changed until the browning disappeared, 

 the pieces then were treated with water, methylated spirit, absolute 

 alcohol, clove oil, and turpentine oil, imbedded in paraffin, freed 

 from paraffin with xylol, and mounted in Canada balsam. 



* Zeitschr. f. Wiss. Mikr., iii. (1886) pp. 50-1. 



t See this Journal, ante, p. 710. J Ibid., p. 709. § Brain, 1885, pp. 227-42. 



