REPORT OF COMMISSIONERS OF INLAND FISHERIES. 193 



larvae it usually appeared that a greater number would remain in the 

 sanded region. In the case of the fifth-stage lobsters, moreover, a 

 very definite tendency to remain in contact with the sand, to burrow 

 in it and not to be dislodged, was most clearly manifested. 



Reactions Determined by Hunger. — Many students of animal be- 

 havior have learned that the condition of hunger is able to greatly 

 modify the reactions of organisms to many stimuli, especially to food. 

 Generally speaking, it has been found that hunger prevents the 

 manifestation of the normal type of reaction. The effect of hunger 

 upon certain stages of Homarus is no exception to this rule. In 

 this instance, however, the condition of hunger appears to be instru- 

 mental in modifying the reactions of the lobster only in the fourth 

 and later stages. To a certain degree this has an explanation in the 

 fact that the larval lobsters of the first three stages are not able to 

 direct their own activity in a definite direction, as toward food ; and 

 it is not until this fourth stage is reached that the lobster is at all 

 the master of its owai progress. It was learned in the early part of 

 the investigations on the behavior of the fourth-stage lobsters that, 

 if any study of their reactions to light was to be made, the lobsters 

 must first be fed — and well fed. For, if such was not the case, the 

 tendency to eat one another usually annihilated any possible mani- 

 festation of a response to the influences of light. Even if the condi- 

 tion of hunger did not excite these extreme cannibalistic instincts, it 

 usually produced a manifestation of unrest which made any results, 

 in the way of numerical counts, impossible. As has been shown, the 

 fourth stage-period — at least in the early part — is the "swimming 

 period" of the lobster's existence. It is not until the latter part of 

 the fourth stage-period that the lobster, under proper conditions of 

 environment, goes to the bottom and begins to burrow in the sand 

 or under the bits of shell. Now it was found that the condition of 

 hunger appeared to have a very definite influence upon the time at 

 which the '-burrowing instinct" was first "liberated." To ascertain 

 more fully regarding this point several experiments were performed; 

 of which the following is a fair example of all : 



