REPORT OF COMMISSIONERS OF INLAND FISHERIES. 295 



series which did or did not regenerate the cheHpeds before the next 

 molt occurred. A comparison of the relative lengths of these lines in 

 each successive section shows that, beginning at the left with series 

 C4, in which all the mutilations were followed by regeneration, there 

 was a gradual decrease in the number of regenerating individuals and 

 a corresponding increase in the number of non-regenerating in- 

 dividuals, to such an extent that, in series C^g, only two of the nine 

 specimens had regenerated the chelipeds. In other words, the 

 difficulty encountered in introducing the process of regeneration at 

 later stages of the molting period increased to such a degree that over 

 77 per cent, of the mutilations made in the later part of the period 

 were not followed by the regeneration of the chelipeds. 



Accordingly, therefore, it seems evident that the process of re- 

 generation does not respond with equal readiness to mutilations 

 made at an}^ time in the molting period; but that it varies according 

 to the time of mutilation; so that while in the earlier part of the molt- 

 ing period the process of regeneration practically always succeeds a 

 mutilation, in the latter part of the period, on the contrary, the 

 chances that a mutilation will be followed by the regeneration of the 

 limbs may be reduced by as much as 77 per cent. 



The Effect of Regeneration upon the Rate of Grow^th of 

 THE Lobster. 



It is a well-known fact that the lobster, as well as most crustaceans, 

 increases in size and to all appearances grows only at certain periods; 

 i. e. the time of molting. But of course this increase in size is not 

 due to growth merely at the time of molting. The facts are that 

 the animal has been growing more or less continually throughout the 

 whole interval between two successive molts; but the hard chitinous 

 shell or exoskeleton will not expand sufficiently to accommodate the 

 growing organism; therefore the developing tissues and organs must 

 increase in mass and compactness till the time of molting, and mean- 



