EXPLANATION OF PLATES 



All the figures represent specimens of Paramaecium aurelia, except figure 34. 

 The animals figured in red were fixed with sublimate-acetic and stained with 

 Ranvier's picrocarmine ; those figured in blue were fixed in Schaudinn's sublimate- 

 alcohol and stained with Delafield's hematoxylin. The drawings were made from 

 total preparations, with Abbe camera lucida, Zeiss homogeneous immersion 2 

 mm. and compensating ocular 12, with drawing board level with stage of micro- 

 scope. Magnification, about 1500 diameters. Reduction for plates, one-half, 

 which has obscured some micronuclear details. 



503 



