420 



JENNINGS— HEREDITY IN PROTOZOA. 



[April 24, 



Table IX. 

 Con-elation Table for Length and Breadth of 262 Unseparated Halves of 

 Dividing Specimens, in which the Depth of Constriction was less than 

 four microns. All descendants of the single individual D, and taken from 

 the same culture on the same day. 



Length in Microns. 



78 80 82 84 



go 92 94 96 98 100 102 



Mean Index, 63.136 per cent.; Coef. Cor., 6546 ± .0337. 



halves in which lengthening had begun, and of the random sample, 

 are given in the first three rows of Table VIII. ^ 



We will for the present limit the discussion to the relations 

 shown by comparing the youngest stages (row i) with the random 

 sample (row 3) which consists mainly of adults. The following 

 important facts are shown : 



1. The mean length of the youngest stages of the new individuals 

 is considerably less than one half of the mean length of the indi- 

 viduals that are not dividing. The mean length of the young is 

 87.848 microns, while that of the individuals not dividing is 199.960 

 microns, or 24.264 microns more than twice the mean length of the 

 young individuals. This remarkable relation will be taken up later, 

 in discussing the measurements of dividing specimens (page 443). 



2. The mean breadth of the youngest stages is slightly greater 

 than that of adults not dividing— 55.480 microns, in place of 50,220 

 microns. 



'In Tables VIII. and IX. the measurements were made and the constants 

 were first computed, for the entire dividing specimens. The constants for 

 the halves were of course readily obtained from these ; they are the same, 

 save that the mean and standard deviation for length are halved, and the 

 mean index is doubled. The computation of the probable errors was based 

 on the number of dividing specimens, not on the number of halves. 



