REPORT OF COMMISSIONERS OF INLAND FISHERIES. 113 



the corresponding pelagic habit; none have the functional chelse or 

 "big claws" of the adult lobster. 



According to the observations made by Doctor Hadley at our sta- 

 tion the average measurements of the three successive larval stages 

 are 8, 9^, and 11 millimeters, respectively. There is, however, a con- 

 siderable range of variation in size, particularly in the second and 

 third stages, and there is good evidence that in general the larger 

 specimens are the better fed. For this reason the average size of the 

 lobsters of the various stages in particular rearing experiments forms, 

 perhaps, a basis for judging whether the lobsters are doing well or 

 not. 



The length of the combined larval stages varies greatly and is 

 directly and powerfully influenced by the temperature and food. It 

 ranges from nine to more than twenty-five days (twenty-one days is 

 extremely long at Wickford). From the viewpoint of practical 

 culture, the length of the total larval period is of very great import- 

 ance, though the duration of the first, second, and third stages sever- 

 ally does not seem to be so. 



DIFFICULTIES IN REARING. 



In artificial culture, of course, the fry must be confined in large 

 numbers, and it is practically impossible to separate them from one 

 another. Therein appears an initial difficulty which all experi- 

 menters have had immediately thrust upon them. The fry, under 

 these circumstances, at once exhibit a most unnatural and vicious 

 cannibalism which Professor Morgan might well have added to his 

 enumeration of characteristics impossible of development through 

 natural selection and the survival of the fittest, for it can hardly be 

 exercised at all under natural conditions. But whether this evil in- 

 stinct arises from one or another biological antecedent cause or is a 

 special inspiration in each particular case, its reality is a constant and 

 serious menace to lobster culture operations. The cannibalistic 

 tendencies are manifested as soon as the fry are hatched and continue 



