196 REPORT OF COMMISSIONERS OF IXLAXD FISHERIES. 



XII. Influences Which Determine the Rate of Growth. 

 Inherited Physiological Condition. 



Before leaving the subject it is not inappropriate to consider briefly 

 the influences which may modify the rate of growth of the lobster 

 under both artificial and natural conditions. Among these we may 

 expect to find such factors as temperature, light, food supply, parasites, 

 injuries, and certain individual or group peculiarities which, as is the 

 case with so many other forms, must be attributed to inherited physio- 

 logical conditions; for there are breeds of large and small lobsters just 

 as truly as there are varieties of large and undersized individuals of 

 the human race. These differences may be observed even in the egg, 

 and can be traced through successive stages in which the characteris- 

 tics in question are manifested either by producing large or small, 

 regular or malformed, individuals.* 



Provided that the food supply is adequate, it is probable that ivater 

 temperature is the influence which most modifies the rate of growth of 

 young lobsters under both natural and artificial conditions. This influence 

 may produce a difference in the rate of growth, not only of small groups 

 of lobsters at different times in the same season and in the same lo- 

 cality, but also of larger groups of lobsters in different localities where 

 they are subjected to still greater differences in the prevailing water 

 temperatures. The results of individual or group physiological con- 

 stitution are no doubt partly due to hereditary causes, and are mani- 

 fested in the difference in size and condition of lobsters when all other 

 factors are equal. These results may, however, often be obscured 

 by the influence of temperature, food, or, in the case of artificially 

 reared lobsters, by other subtle influences, such as light or physical 

 environment, etc. These facts are demonstrated by a comparison 

 of Tables Nos. 25 and 26. That one of these groups of lobsters (Table 



*Although we know that there is a great variation in the normal size of the mature egg, 

 there still remains a question to be answered as to whether the prevailing temperature of the 

 water shortly previous to the time of hatching may not exert an important influence in deter- 

 mining the size and condition of young lobsters directly after hatching. 



