358 MANII'ULATION. 



points are accomplished; at the lower end of the compound 

 body, immediately above the object-glass, x, a prism, a, is 

 introduced to erect the image of the object, g ; the lower lens, 

 c c, of the eye-piece is of the ordinary construction, but that 

 of 6 c? is a prism having its lower surface convex and its upper 

 one, o, plane ; by these means the rays of light from the object 

 are bent at an angle of about 45", and the image is seen in the 

 direction of the line o d. This microscope is fully described by 

 M. Robin in his work Du Microscope et des Injections; from 

 which the representations given in the preceding page have 

 been copied ; the compound body can also be adapted to the 

 upright form of instrument before described in page 108. 



If the subject to be dissected be a portion of injected 

 mucous membrane, it may be pinned out on one of the 

 loaded corks, and placed in a trough with water; and if it 

 have previously been kept in spirit, it shoidd be well washed 

 in the water before examination by the microscope ; for this 

 purpose the small syringe alluded to in page 351, vs^ill be 

 required. The subject may either be dissected under a lens, 

 or may be from time to time examined by a compound 

 microscope as the dissection is being proceeded with ; for this 

 purpose the instrument described at page 52 may be employed, 

 or one of the kind represented by fig. 237, which the author 

 has found very convenient, and is in the habit of keeping 

 always on the table whilst dissections are being carried on. 

 It consists simply of a tube, « I, forming a compound body, 

 which is capable of being moved up or down in an outer tube, 

 supported on a curved arm, d, by a rack and pinion connected 

 with two milled heads, one of which is seen at c ; the end of 

 the support, d, is made conical at e, so that it may be fitted 

 into a hole in a block of wood, g ; this forms the stage, and 

 on it all the smaller troughs may be placed. The compound 

 body so mounted will also answer for transparent objects 

 when adapted to a stand supplied with a mirror. Such 

 an instrument will be found exceedingly useful, and, without 

 the object-glass and the eye-piece, f, may be procured at a 

 trifling cost. 



