OP MICROSCOPIC OBJECTS. 18 



are very beautiful transparent objects. Some of the finer 

 tissues, also, are shown much better by this mode of in- 

 jection than by the opaque, and are easily mounted by 

 washing in clean water when first separated, and floating 

 upon a slide, where they must be allowed to dry thoroughly. 

 They may then be immediately mounted in balsam, or kept 

 in the dry state until it is convenient to finish them ; but 

 in many cases this keeping, if too much prolonged, will 

 injure the object. If it is desired to transfer the section to 

 another slide, it will be necessary to wet it thoroughly with 

 water by the aid of a camel-hair pencil, and then gently 

 strip it off with the forceps. When it is wished to preserve 

 injected subjects in masses, it must be done by immersion 

 in spirit, and the sections may be cut at leisure. Most of 

 these transparent objects may be mounted in Canada 

 balsam ; but some recommend glycerine or glycerine jelly, 

 as allowing the use of a higher power in their examination ,. 

 and preserving them in a more natural form. 



34. A few subjects may be noticed which are very beauti- 

 ful when injected, and amongst these are the eyes of many 

 animals. They must be injected by the artery in the back 

 part, and when the blue transparent liquid is employed, 

 nothing can exceed the delicate beauty displayed by some 

 of the membrane. It must be dissected with care, but well 

 repays us for the trouble. Water-newts and frogs are not 

 difficult subjects, and in their skin and other parts are many 

 interesting objects. Amongst the commoner animals rats, 

 rabbits, cats, &c. almost endless employment may be 

 found, making use either of portions or the whole animal at 

 once. The intestines of many of these are very beautiful. 

 We must divide them with a pair of scissors along the tube, 

 and cleanse them from the contents; the specimen may 

 then be laid upon a slide, and any remaining impurity 

 removed by a camel-hair pencil and water. When dried it 

 may be mounted in balsam, and having been injected with 

 the transparent blue, its minute beauty is shown most per- 

 fectly In injecting a sheep's foot, which is a good object, 



