/2 GARY N. CALKINS. 



PLATE III. 



FIG. 18. a, dividing cell cut in zone 2 of the posterior cell; b, fragment 24 

 hours after the operation; c, fragment 3 days after the operation. Experiment 6, 

 Table II. 



1 1 1.. 19. a, vegetative cell cut in zone 3; b, anterior fragment 48 hours after 

 the operation; c, attempted division resulting in monster formation mi the third day 

 aiit-r cutting. Experiment 6, Table III. 



FH.. 20. a. vegetative cell cut in zone 2; b, posterior fragment 12 hours after 

 the operation; c. asymmetrical division of b, 24 hours after the operation; d, e, normal 

 and abnormal cells resulting from the division of c; f, attempted division of c 48 

 In mis alter the operation; g, h, results of a second (double) division of / on the 

 fourth day: /;. a normal Parameciitm derived from the upper branch of g; this 

 li\i-d for 48 hours and attempted to divide but died in the process; i, mon-trr 

 derived from g on the sixth day, with two practically complete paramecia and 

 several papilliform buds;,;', same monster on the ninth day; k. a detached free 

 cell on the ninth day derived from the upper cell shown in figure i\ I, same monster 

 on the twelfth day with constriction due to a girdle of zooglcea; m, same monster 

 on the thirteenth day with individuals partially withdrawn; n, a third, free indi- 

 vidual given off on the twelfth day, this being the attached individual on the left 

 side of Fig. 1; o, same monster on the fourteenth day with eight Ptirnmcdnm buds, 

 six mouths additional (not shown) and ten vacuoles. As the figure shows the mass 

 \\.i-againconstrictedand this time the constriction resulted in division but the 

 daughter monsters were dead on the next day. Experiment 25, Table II. 



