THE USE OF THE MICROSCOPE. 353 



TABLE VII. 



OF INJECTING WITH OPAQUE AND TRANSPARENT MATERIALS. 

 PRUSSIAN BLUE FLUID FOR INJECTION. 



46. Arrange the injecting apparatus conveniently ( 165) and proceed 



to inject the artery supplying the eye-ball of the ox's eye on the 

 table, with size and chromate of lead. 167, 170, 186. 



47. Eye. Introduce the pipe into the vessel running close to the large 



optic nerve, and tie it carefully, observing the precautions de- 

 tailed in 1 86. The eye must be allowed to remain in warm 

 water until warm through, and the injecting material prepared in 

 the manner described ; it is to be mixed with melted size and 

 strained immediately before use. When the injection is com- 

 plete the eye is to be placed in cold water. Should it become 

 very much distended by the accumulation of the injection 

 within it, a puncture may be made in the cornea, which will 

 permit the escape of the aqueous humour, and then the vessels 

 may be more completely injected. 186. 



48. Prepare some Prussian blue injecting fluid. 178. 



49. Frog. Insert an injecting pipe into the aorta of the frog in the 



manner described in 186, and slowly inject the fluid. 



50. The specimens having been completely injected portions maybe 



submitted to microscopical examination. 212. 



51. The globe of the eye may be opened and portions of the follow- 

 ing tissues removed with scissars, ciliary processes situated 

 behind the iris, the retina (the most intenial of the membranes 

 within the globe), the choroid (external to the delicate retina). 

 These, after having been carefully washed in water, may be sub- 

 mitted to examination in fluid with the inch object-glass. 



The ciliary processes and the choroid require to be well washed 

 in order to remove the black pigment with which they are 

 covered. 



52. Portions of the lung and intestines of the frog may be removed, 



and after being well washed, may be submitted to examination 

 These are to be examined by transmitted light, and may be 

 placed in glycerine. The inch object-glass should be employed 

 in the first instance, and afterwards the quarter. 



2 A 



