OP 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. 



SND 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, hsematoxyline, 

 &c., formulae 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 

 strength 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 



