VII. KXPLAXATIOX OF PLATES 



All the figures represent spL'cimens of Paramaecium caudatum. The animals 

 were fixed in Schaudinn's sublimat-alcohol and stained withDelafield's hematoxy- 

 lin. 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 microscope. Magnification, about 1500 diameters. 

 Reduction in rfjiroducing plates 1, 2, 3, 4, 5 is one third; plates 6 and 7 is one 

 half. 



PLATE 1 



KXPLAXATIOX OF FI(;UKES 



1 Culture Y, Line lY. 85th generation, April 3, 1914. Xornial animal in a 

 period when endomixis is not in progress. 



2 Culture Y, Line IV ae, 136th generation, April 28, 1914. Typical animal 

 just at the start of endomixis. 



3 Culture Y, Line III fa, 203d generation, .June 8, 1914. Animal just in a 

 ver}^ early stage of endomixis. Alacronucleus wrinkled. Micronucleus has 

 shifted from its typical position close to the macronucleus. 



4 Culture Y, Line III fb, 2G3d generation, June 8, 1914. Animal in a slightly 

 more advanced stage than the one shown in figure 3. 



5 Culture Y, small tube culture, about 137th generation, April 22. 1914. 

 Start of the first 'reduction' division. 



f) Culture Z, Line IV, 184th generation, December 24, 1914. Macronucleus 

 partly devoid of chromatin. First 'reduction' division nearly completed. 



84 



