No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 
401 
little could be gained from a study of the living cells, in regard 
to the minute structures with which we are chiefly engaged. 
With only few exceptions (Rodalia and the two gregarines 
examined) no cells were studied which had not been preserved 
with at least three fixing reagents, and in some cases at least 
half a dozen different fixatives were used. The preserving 
reagents employed were the following: saturated solutions of 
corrosive sublimate in distilled water (this being the only fluid 
used hot), sat. sol. of the same in 50 jo or 35 jo alcohol, Flem¬ 
ming’s stronger fluid (chromo-aceto-osmic acid), Hermann’s 
fluid (platinum chloride, acetic acid, osmic acid), sat. sol. of 
picric acid in 50 jo alcohol, Perenyi’s fluid (chromo-nitric acid), 
2 jo aqueous sol. of chromic acid, absolute alcohol, picro-nitro- 
osmic acid. Those reagents which gave the best general results 
were the fluids of Flemming and Hermann, and the alcoholic 
solution of corrosive sublimate ; though the particular reagent 
demanded depends both upon the object of study, as well as 
upon the method of staining which is to follow. It is hardly 
necessary to state that a structure found after the use of a 
given fluid, but not apparent on material treated in a different 
manner, was either regarded as an artefact, or doubts were 
expressed as to its naturalness ; that is, only when a structure 
was found to present itself to the eye in more or less the same 
manner, after various methods of preservation had been 
employed, have I regarded it as a natural appearance and not 
as a result of the fixatives used. Thin serial sections were cut 
of objects imbedded in paraffin, in the usual way. All staining 
done was upon the sections on the slide, and the stains employed 
were as follows : Ehrlich’s or Delafield’s haematoxylin followed 
by eosin (sat. sol. in distilled water), nigrosine (a sat. sol. in water 
diluted by six vols. water), sat. sol. of acid fuchsine in 50^ alco¬ 
hol, the triple stain of Ehrlich-Biondi-Heidenhain (as prepared 
by Griibler, Leipzig), Flemming’s triple stain (safranin, gentian 
violet, and orange G.), Lyons blue (sat. sol. in 50^ alcohol), 
gentian violet (sat. aqueous sol.), methylen blue (sat. aq. sol.), 
brasilin (sat. sols, in water and in 35^ alcohol), Mayer’s acid 
carmine, cochineal (sat. sol. in 70ft alcohol); while Grenacher’s 
borax carmine and alum carmine, Heidenhain’s iron haematoxy- 
