PLATE IS. 



Zeiss microscope stand II". 



This form of microscope and that represented on plate 16 are the two patterns used princi- 

 pally in the Laboratory o( Plant Pathology, U. S. Department of Agriculture. The 

 objectives are apochromatic. and have proved very serviceable. In carrying do not grasp by 

 any part above the level of the stage, as this brings an undue weight upon the fine adjust- 

 ment. Seize by the base. 



