THE PROBLEM 



31 



occurred, we may with reasonable assurance conclude 

 that this animal is immortal. 



Of even more probative value, in the opinion of 

 some workers, than the results on Paramecium are 



FIG. 3. Paramecium, viewed fron the oral surface. L. left side; R, right side; an., anus; 

 ec., ectosarc; en., endosarc;/. v., food vacuoles; g, gullet; TO, mouth; ma., macronucleus; mi., 

 micronucleus; o. g., oral groove; P., pellicle; tr., trichocyst layer. The arrows show the 

 direction of movement of the food vacuoles. (From Jennings). 



the recent experiments of Hartmann, who cultivated 

 Eudorina elegans for over 600 generations without con- 

 jugation or any nuclear reorganization corresponding to 

 endomixis, and no depression in the culture occurred. 

 The distinction between Protozoa and Metazoa in 



