igos.] JENNINGS-HEREDITY IN PROTOZOA. 445 



ning fission than in the others. In the former the coefficient is but 

 9.082, while in the latter it is 12.877. 



7. The mean index, or ratio of breadth to length, is much greater 

 in the specimens beginning fission; in these it is 31.568 per cent., as 

 contrasted with 25.114 per cent, in the random sample. 



8. The correlation between length and breadth is high in the 

 specimens beginning fission; it is somewhat greater than in the 

 random sample. In the former it is .6546 ; in the latter .6064. 



Owing to the smaller numbers in the other lots of dividing speci- 

 mens, I included in the group " beginning fission " all those in which 

 the depth of the constriction below the body surface was less than 

 one fourth the breadth of the animal. Thus, all specimens with 

 constriction 12 microns deep, or less, were included. Of course, 

 these groups contained specimens in decidedly more advanced stages 

 of fission than in the large group we have been considering. The 

 numbers of specimens in early stages of fission thus secured were 

 respectively 40 (Table XLIII.) and 42 (Table XLIV.). The con- 

 stants for these, in comparison with random samples or adults, are 

 shown in Table X. (rows 24 and 30). 



As the tables show, these manifest in most particulars the same 

 relations which we have brought out above for the larger and more 

 precise set containing 131 specimens. The difl'erences between the 

 dividing specimens and the other individuals (as shown by the random 

 samples, etc.) are in the main somewhat less in amount than in our 

 first example. This is because in the smaller lots specimens are- 

 included in which lengthening and narrowing had begun, causing the 

 dimensions to approach those of the specimens not dividing. 



The most striking difference between our large lot (Table X.,. 

 row 25) and the smaller ones (Table X., rows 24 and 30) is in the 

 correlation between length and breadth. While in the larger lot the 

 correlation was high, in the smaller ones it is small or quite lacking. 

 This is again due to the inclusion of more advanced stages in the 

 smaller lots ; as the length increases the breadth decreases, tending to 

 destroy the correlation. 



Descendants of c {aurelia Form). — Two lots of dividing speci- 

 mens were examined from the descendants of the small individual c. 

 The first contained 119 specimens (Table XLV.) ; the second 63 



