1900] MICROSCOPICAL JOURNAL. 243 



that Cocci, especially in Zoogloea, could be obtained by 

 various nuclear stains, for this purpose, and for the first 

 time he used an anilin dye, viz., Methyl Violet. 



These anilin dyes, destined, in a great measure, to dis 

 place carmine and haematoxylin, were first put on the mar- 

 ket in 1856, and although recommended by Waldeyer in 

 1863, were still very little used. Fischer, however, in 1875 

 introduced Eosin, much used at present as an ingredient 

 in multiple stains, and also for blood work ; and about the 

 same time, Ehrlich threw the weight of his authority into 

 the scale ; in 1878 we find Weigert recommending the use 

 of Bismarck Brown, and in the next year Ehrlich pub- 

 lished his far-reaching classification of the coal tar colors, 

 dividing them into three groups, the Basic, the Acid, and 

 the Neutral ; the first class being, in general, sharp nu- 

 clear stains, the second, plasma stains, that is to say, 

 stains with a special affinity for cytoplasm, and intercel- 

 lular substances; and the last, stains with special affinity 

 for certain cell contents ; this classification, with one or 

 two reservations, is accepted as correct at the present day. 



In the year 1871 Ehrlich conclusively demonstrated 

 that only the basic colors were suitable for bacteriologi- 

 cal investigation : Bismarck Brown, Fuchsia, Methyl, and 

 Gentian Violet, etc., but especially Methylene Blue. 



The tide had now turned completely in favor of the ani- 

 lins, and the next few years are particularly rich in the 

 application of these dyes to the various branches of mi- 

 croscopic research. 



Weigert applied Acid Fuchsin to the study of the ner- 

 vous system ; Strasburger used Methyl Green, combined 

 with acetic acid, to demonstrate the mitotic figures of cell 

 division ; and in the same year, 1882, Koch demonstrated 

 the Bacillus tuberculosis by staining first with alkaline 

 Methylene Blue, and subsequently with Vesuvin, whereby 

 the Bacilli were stained blue, the remainder, including 

 other micro-organisms, brown. This method was modifi- 



