2 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



washed, and hardened in alcohol. Small pieces were im- 

 bedded in paraffine in the usual way, and sections 5 to 7 )«, 

 thick were cut and mounted in series. For in toto prepara- 

 tions, portions of the respiratory tree were stained, washed, 

 and run into glycerine or through alcohols, followed by 

 clove oil, teased upon the slide to free the infusoria from 

 the respiratory membrane, and mounted in glycerine, glyc- 

 erine jelly, or balsam. 



A large number of fixing agents were tried: picro-acetic, 

 picro-sublimate-acetic, Gilson's fluid, sublimate-acetic, 

 iridium chloride-acetic, Flemming's strong and weak solu- 

 tions, Vom Rath's solution, platinum chloride-acetic, Her- 

 mann's fluid, absolute alcohol, absolute-acetic, palladium 

 chloride, Rabl's fluid, bichromate-osmic, and osmic vapor. 



Hermann's fluid gave the best results, though sublimate- 

 acetic, absolute-acetic, Boveri's picro-acetic, Flemming's 

 and Vom Rath's solutions proved quite satisfactory, and 

 osmic vapor was especially valuable for temporary in toto 

 preparations in the study of division stages. 



Peptone and pepsin solutions, bichromate of potash (one 

 to three per cent.), formalin (one-tenth to one per cent.) 

 and fresh water were employed as macerating agents; of 

 these, potassium bichromate (two per cent.) was found to 

 be of greatest value in revealing and isolating the internal 

 fibre structures of Licnophora. 



The principal stains used were Delafield's hematoxylin, 

 dahlia, bismark brown, thionin, methylen blue, acid fuch- 

 sin, borax carmine, alum carmine, picro-carmine, Mayer's 

 paracarmine, light green, safranin, Heidenhain's iron- 

 haematoxylin, rubin, and ruthenium red. For fresh mate- 

 rial picro-carmine and alum carmine gave the best results; 

 borax carmine, paracarmine, light green, and safranin were 

 useful in the study of fixed material in toto; for sections no 

 other stain was at all comparable to Heidenhain's iron- 

 hsematoxylin following Hermann's fixing fluid, and used 

 either alone or in combination with rubin or with ruthenium 

 red. 



