LIFE HISTORY OF TWO RARE CILIATES 389 



plasma-relation on favor of the protoplasm. In table 3 are 

 given the measurements of twelve cells in division stage, the 

 average kernplasma-relation 1:12.8 showing a return to the 

 • kernplasma-norm, the average coefficients recorded in tables 1 

 and 3 being identical. An analysis of the relations existing 

 between nucleus and protoplasm in new cells, vegetative cells, 

 and division-stages show, first, that the nucleusplasma-norm 

 expressed by the ratio 1 :13.3 is destroyed during the period of 

 time immediately following division, the ratio between the nu- 

 cleus and protoplasm being almost doubled in favor of the latter: 

 second, that in the division stages the norm is re-established. 

 These conclusions based on average measurements, agree in 

 the main with the results of Hertwig and Popoff. 



Popoff ('08), in his study of Frontonia leucas, in discussing 

 the relation between the depression periods and size variations 

 says, "The animals show during this period a marked decrease 

 in cell size and a disturbed kernplasma-relation in favor of the 

 nucleus." And again, "the researches of R. Hertwig in Actinos- 

 phaerium, Dileptus and Paramoecium, those of Calkins on Para- 

 moecium and of Woodruff on various hypotrichous ciliates, and 

 my own work in Stylonychia proves that the protozoa, through 

 a period of uninterrupted activity, come into a condition in 

 which the nucleus shows an abnormal growth." In regard to 

 Calkins' work, Popoff took for granted that the greatly enlarged 

 nucleus was the cause of the depression. Since Calkins, in 

 his paper of 1904, makes no reference to the kernplasma-relation, 

 PopofT must have drawn his conclusions from the photographs 

 of the cells and did not take into consideration the fact that 

 the cells had not divided for several days and were therefore 

 in an abnormal condition. 



In table 4 I have recorded the length, diameter and volume 

 of protoplasm and nucleus of newly divided cells, vegetative 

 cells and division stages chosen from two periods in the life- 

 history of Spathidium. The cells represented in the first column 

 were taken from the cultures during a ten-day period in March 

 when the division energy was high, averaging for the period 

 3.1. The figures of the second column are measurements of 



