ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



315 



This can be remedied by inclining the Microscope to an angle of 

 40''-45° and altering the position of the camera prisms as shown in 



Fig. 57. 



Fig. 58. 



fig. 57. A drawing thus made will be undistorted if its axis (a' o) is 

 exactly perpendicular to the surface 

 of the table. For this, however, it 

 is necessary that the axis should fall 

 on the line x y, and that it should 

 make with the axis of the Micro- 

 scope an angle (a o a') equal to the 

 angle of inclination of the Micro 

 scope. 



Fig. 58 shows M. Malassez's 

 modification of a Doyere and Milne- 

 Edwards camera to meet these con- 

 ditions. One of the prisms can be 

 rotated by a milled head and adjusted 

 for the 45° position, or where the 

 objects must be kept horizontal and 

 the Microscope therefore vertical it 

 can be set for an angle of 18''. The 

 modification can be applied to other 

 camerae, but where the reflecting 

 surfaces are not movable the original construction must be altered. 



The author considers that Dr. Schroder's camera is objectionable, 



