Dogiel (1866) introduced a combination of carminates with acetic 

 acid. Haematoxylin was first introduced as an histological stain 

 by Bohmer (186.5), altho a previous rather unscientific attempt had 

 been made by Waldeyer (1864) to stain axis-cylinders by means of 

 the watery extract of logwood. Bohmer's greater success was due 

 to his use of haematoxylin crystals in combination with alum, 

 either by accident, or else because he knew that it was frequently 

 used as a mordant in textile dyeing. Slightly later Frey (1868) 

 showed that similar results could be obtained by mixing the mor- 

 dant with the solution in which the tissues were fixed before they 

 were stained. 



Double staining was introduced at about this same period, when 

 Schwarz (1867) proposed fixing tissue in creosote and acetic acid, 

 then staining 24 hours in very dilute ammonium carminate, and 

 subsequently washing and staining for two hours in picric acid. A 

 year later Ranvier (1868) first used a picro-carmin stain to obtain 

 the same results by a single procedure. 



Anilin dves had become commercial articles before all these ad- 

 vances with the natural dyes had been made, the first one having 

 been introduced in 1856 when Perkin prepared mauveine. Fuch- 

 sin, under the name of anilin red, appeared in 1858. The first sug- 

 gestion of their use in histology seems to have been made by 

 Beneke (1862), who used acetic acid colored with a lilac anilin, 

 probably a mauveine or anilin violet; while two years later Wal- 

 deyer (1864) used anilin red (fuchsin) and also a blue and a violet 

 anilin dye. The latter investigator observed the ability of fuch- 

 sin to stain nuclei more deeply than cytoplasm and the axis cylin- 

 der more deeply than the medulary sheath of nerves. 



The principle of differentiation following staining was soon in- 

 troduced. Bottcher (1869) differentiated his sections by partially 

 decolorizing with alcohol after staining with rosanilin nitrate. A 

 very similar method was later published by Hermann (1875), who 

 is often mistakenly given the credit for originating the principle. 

 Later the same procedure was further investigated by Flemming 

 (1881) who tried both acid and basic dyes, finding that the method 

 was satisfactory only in the case of the latter group. 



Gierke (1. c.) in his historical discussion of staining says that the 

 history up to his day (1884) was divided into three periods, each 

 occupying a decade. The first decade, the fifties, was character- 

 ized by a few important but unrelated discoveries, which ended in 

 the work of Gerlach, each investigator following up accidental 

 observations on the staining powers of carmin and the other well- 

 known dyes of those days. After Gerlach's work the development 

 of the technic in the sixties was more rapid and depended less upon 

 chance success by the individual investigator; the effort was made 

 to use similarlv all the dves and metallic colors then available. The 

 next decade would have had much less left to develop in this line if 

 it had not been that by this time the great variety of anilin dyes 



9 



