44^ Gary N. Calkins. 



The papillae of the cuticle were plainly visible and what T have 

 taken to be apertures of the trichocysts were more or less 

 numerous. (This is shown in the preserved sister-cell, Fig. 22.) 

 A few trichocysts remained in the cortical plasm, but there were 

 many vacuoles in this layer indicating that when the trichocysts 

 were discharged they were not re-formed. The peristome was 

 normal and the mouth had a vigorous oral membrane. The 

 size was large, fully as great as any of the preparations that 

 had been made at any time during the 742 generations. Move- 

 ments vigorous to slow, with a tendency on the part of the animal 

 to remain stationary." ^ 



It was while the organisms were in this structural condition that 

 the many attempts to rejuvenate the race were made as described 

 in the previous pages, and it was in this condition of the proto- 

 plasm that the race finally died out from exhaustion. Before 

 dying, however, the individuals, as indicated in the above para- 

 graph from my notes, were of full size and were filled with gastric 

 vacuoles and partly digested food, while the body form was 

 normal, (compare Figs. 2 and 21). 



It must be admitted that these forms were capable of individual 

 growth at this period and, since the macronucleus was normal in 

 the last individuals luhile the micronucleus was considerably 

 changed, it must be further admitted that the vegetative metabolic 

 processes were presumably reinvigorated; on the other hand, the 

 functions of reproduction; that is, of division, were degenerated 

 possibly, if not probably, because of the apparent degeneration of 

 the micron-ucleus and of the cortical plasm, whose functions were 

 not reinvigorated by the artificial means which were tried. 



IV. GENERAL DISCUSSION. 



Although only a beginning has been made to determine the 

 objects for which this series of experiments was started, it is 

 advisable to bring together the results thus far attained and to see 

 how they conform with the a prion conceptions which were cur- 

 rent at the outset of the experiments. 



1 From my note book. 



