THE AMERICAN LOBSTER. 



!)9 



Vitzou records the following observations {107) upon the increase iu size and 

 weight of molting lobsters. Ln a lobster which was measured immediately before and 

 after the molt it was found that the carapace had gained 11 mm. iu length and the 

 abdomen 8 mm. The last joint of the right claw was smaller by 3 mm., which is 

 explained, first, by the thickness of the chitinous layer in this joint, and, secondly, by 

 the almost complete absence of blood in the claw at this time. This is a forced con- 

 dition, since if the last joint of the claw were increased in size it would be next to 

 impossible for it to be withdrawn (see pp. 86-87). The same lobster 17 hours after the 

 molt showed no increase iu size of carapace or abdomen, but the claws had gained from 

 12 to 15 mm. in length. No increase in any of these parts was noticed on the third to 

 the sixth days following the molt, but there was a gain in weight. 



Table 27. 



Time of observation. 



Immediately alter molt 



The day following molt 



Third day following molt 



Fourth day following molt 



Fifth and sixth daysfollowing molt 



Weight. 

 Grams. 



Increase. 



Grams. 



500 

 610 





100 



619 



9 



642 



23 



642 







The following measurements show the increase in various parts of the body after 

 the molt. They refer to lobster No. 6, table 21 (compare plates 45a, and 45ft) : 



Tablk 28. 



Measurements. 



Before 

 molt. 



Inches. 



Length 9. 28 



Length of carapace | 4. 33 



Greatest width of carapace i 2. 2 



Length of crushing-chela (propodus) I 4. 12 



Width of crushing-chela at base of dactyl.. 2.06 



Length of dactyl 1. 90 



Width of dactyl at base .72 



Length of small cutting-chela (right) 4. 53 



Width of small cutting-chela 1. 53 



Length of dactyl 2.53 



Width of dactyl ] .56 



Five days 

 after molt. 



Inches. 

 10.50 

 5.03 

 2.33 

 5.62 

 2.56 

 2.25 

 1.00 

 5.53 

 1.47 

 3.06 

 .65 



Increase. 



Inches. 



1.22 

 .70 

 .13 



1.50 

 .50 

 .35 

 .28 



1.00 



— .06 



.53 



.09 



