252 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



we might come, is that in all probability, full sunlight is detrimental 

 to the development of the young lobster, but that weak sunlight or 

 twilight exerts the most accelerating influence upon the rate of 

 growth. We will now see what evidence there is to demonstrate 

 the probable truth of this hypothesis. 



We know first of all that the lobster is an individual whose habits 

 of life seldom lead him beyond the twilight of his natural haunts. 

 We know that when strong lights are brought to bear upon, young 

 adolescent lobsters they at once become restless, wander nervously 

 about their cars, often refuse to touch food, and at all times manifest 

 a definite effort to retreat from the light rays. Believing that the 

 sunlight was unfavorable to the development of the lobsters, even 

 after the fourth stage, the writer provided covers for most of the 

 compartment cars in which the young lobsters were confined (Plate 

 XXXV), thus producing in them the effect of twilight. Although 

 the results obtained from these experiments do not justify far- 

 reaching conclusions, they are nevertheless indicative of the fact that 

 the condition of twilight does, for several reasons, actually prove 

 beneficial to the developing lobsters; and that, on the other hand^ 

 broad sunlight is detrimental to their growth, first by increasing the 

 length of time between each molting period, and second, by diminish- 

 ing the amount of increase in length at each molt. The facts which 

 lead to such a conclusion may be briefly presented in the tables which 

 follow. 



The lobsters in the groups indicated by the heading "in twilight" 

 were raised from the third stage in the individual compartment cars 

 already mentioned. They were quite protected from the light above 

 by the broad covers with which the cars were supplied. The only 

 light which was accessible entered through the wire screening of the 

 sides, a large part of which was, in every instance, under water. In 

 the case of those lobsters included under the heading "in sunlight," 

 the compartments were in the form of wire cylinders, each containing 

 in the bottom a saucer holding a small quantity of gravel. These 



