OF MICROSCOPIC OBJECTS. 7 
the tissues are thereby as it were “ differentiated,” yet not 
altered in any material degree. This may be effected by 
solutions of gum, sugar, glycerine, and creosote, if the 
tissues are moist. If dry, then turpentine, Canada balsam, 
benzine or benzole, and the essential oils of cloves, anise, 
and cassia, may be employed. 
Qnp DIvIsION. 
Under the second division of our subject come staining 
fluids. 
- Many of these will be found mentioned in the body of this 
work, They comprise carmine solutions, both acid and 
alkaline; aniline colours, indigo, carmine, hematoxyline, 
&c., formule for the use of which are given. ‘To these Frey 
adds, blue tingeing by molybdate of ammonia, and double 
staining by carmine and picric acid. 
A neutral solution of the molybdate of ammonia of the 
strenoth of 5 per cent. gives a blue tint to nerve-tissue, 
lymphatic glands, and ciliated epithelial cells, after macera- 
tion for 24 hours in the light. 
For double staining by carmine and picric acid he recom- 
mends a mixture containing— 
1 part creosote, 
10 parts acetic acid, 
20 parts water. 
Soak the tissues in this solution while boiling for about a 
minute, then dry for two days. Make thin sections of them, 
immerse for an hour in water faintly acidulated with 
acetic acid, and then wash in distilled water. Next place 
them in a very dilute watery solution of ammoniacal car- 
mine, wash again in water, and place in a solution of picric 
acid in water, the strength of which will vary according to 
circumstances. The sections are then to be placed on a 
slide, superfluous acid allowed to drain off, and a mixture of 
4 parts creosote to 1 of old resinous turpentine dropped on 
