DOUBLE STAINING NUCLEATED BLOOD-CORPUSCLES. 293 



dyes for double staining, as some of the methods recommended 

 had, in my hands, turned out very unsatisfactorily. During 

 the year 1881 I had, at the request of Dr. Vandyke Carter, 

 devoted a considerable time to the preparation and investiga- 

 tion of the organs of patients who had died of " spirillum 

 fever," and also of those of animals which Iiad been experi- 

 mentally inoculated with the fever virus. We wished to de- 

 monstrate in these tissues and organs the presence of spirilla 

 as had been done with ease in the blood. We used, according 

 to the advice of Professor Koch, several anilin dyes in turn 

 with anything but certain results. The indefiniteness, there- 

 fore, of the staining struck me much, and induced me to think 

 that something might be done in the way of obtaining more 

 satisfactory combinations. The demonstration of the bacillus 

 in tubercle has brought into prominence the manipulation of 

 combinations of these dyes, and the fact that since the first 

 process of Koch was introduced, large numbers of modifica- 

 tions of it have been brought forward, notably by Ehrlich, 

 Bauragarten, Ermengen, Gibbes, and others, point to the con- 

 clusion that a considerable amount of work remains to be done 

 before the subject is fully develoded. These experiments in 

 staining the nucleated corpuscles were undertaken, as I have 

 said, with a view of finding out whether, with such definite 

 elements of tissue, certain results could be obtained by staining 

 with certain anilin dyes in solutions of definite strength in 

 regular sequence. 



Method of experiment. — After trying several methods, 

 the one I adopted was as follows : — Blood from various animals 

 — frogs, newts, &c. — was spread in thin layers upon |-inch 

 cover-glasses and allowed to dry in the air. Certain of the anilin 

 colours were then chosen as the first or primary colours ; these 

 were fuchsin, eosin, rosein, and rosanilin, in aqueous 

 or dilute spirit solution, as red dyes; iodine or malachite 

 green, as green dyes; and methyl violet, Hoffman's vio- 

 let, or gentian violet, as violet dyes. All of these were in 

 aqueous or dilute spirit solution. With each primary colour 

 was included a separate series of experiments. Several drops 



VOL. XXIII. NEW SEK. U 



