REGENERATION OF FINS OF FUNDULUS HETEROCL1TUS. 399 



that is, the pectoral in the fed fishes regenerated 24 per cent, more 

 than that in the unfed. 



(E) REGENERATION IN FINS USED MOST COMPARED WITH THAT 



IN LESS USED FINS. 



Adaptation in Regeneration. Osburn ('06) experimenting on 

 the fins in Fundulns finds that the pectorals are not used as 

 vigorously as the caudal, and the dorsal not so much as the 

 pectorals. Broussonet (1786) stated that the most useful fins 

 regenerate more rapidly than those less useful. Morrill ('06) says 

 that the " caudal fin though obviously the most important does 

 not regenerate perceptibly faster than the others." Although 

 the data are insufficient to settle this question which is to a great 

 extent a matter of interpretation yet the following table is sugges- 

 tive. Since it has been shown that degree of injury has made no 

 difference in the rate of regeneration in Fundidus //., it is therefore 

 possible to group all the specimens represented in Table I. thus, 



Average Sp. Reg. of caudal fin in Lots A + B -f- C = 0.08565 



Average Sp. Reg. of pectoral fin in Lots B + C = 0.06770 



Difference ==0.01795 



which means that the caudal fin of specimens in Lots A -f- B -f C 

 regenerated 26 per cent, more than the pectoral fin in Lots B + 

 C in the same time and under same conditions. 

 In the same way from Table II., we find 



Average Sp. Reg. of caudal fin in Lots D -f- F == o. 01016 



Average Sp. Reg. of pectoral fin in Lot F 0.00846 



Difference , ... =0.00170 



or in other words the caudal regenerated 20 per cent, more than 

 the pectoral. 



Again in Table III. the 



Average Sp. Reg. in caudal in Lots G + H -f I ==0.0386 



Average Sp. Reg. in pectoral in Lots H 4- I -= 0.0313 



Difference = . 0.0073 



or the caudal in this case has regenerated 20 per cent, more than 

 the pectoral. Thus in all three cases the result is the same. It 

 should be remembered that specific regeneration is the relation 

 of amount regenerated to the length of the specimen. And hence 

 we have a right to compare the specific regenerations of caudal 

 with pectoral. It may also be pointed out here that the dorsal 



