No. 658] CLONAL VARIATION IN PECTIN ATELLA 



363 



Thus he finds that, in one and the same colony, the 

 mean number of hooks increases with the temperature of 

 the colony when the hooks are being formed and, in sup- 

 port of this contention, gives tables of his countings from 

 the same mass between July and October. Some of his 

 data support this conclusion strongly, as shown in 

 Table I. 



TABLE I 











Inscription of Mass. 



24 



25 

 26 



Aug. 23 



Sept. 14 

 Sept. 14 



Sept. 6 

 Sept. 24 

 Sept. 24 

 Sept. 24 



30 

 12 



145 

 302 



14.33 



17.50 

 18.47 



14.12 

 14.69 



Derived from 5 statol.lasts. 

 Fii>t stiUul.last June 2S. 



Derived from 2 statoblasts. 

 Oldest portion. 

 Peripheral (younger) zone. 



22 



July 16 

 Aug. 3 









In other cases the hypothesis is not sustained as shown 

 in Table la. 



The remaining series have determinations at two dates 

 only and are less significant, though supporting the hy- 

 pothesis, so far as they go. 



Influence of Age on the Number of Hooks 

 In our work, colonies of Pectinatella were grown on a 

 clean board kept at the dam, lowest lake, Cold Spring 

 Harbor, and examined daily. The first young colonies 



