REPORT OF COMMISSIONERS OF IXLAXD FISHERIES. 195 



maiiied on the clean bottom of the jar, over which they crawled or 

 lightly swam. Occasionally one would come to the surface, only to 

 leave it again for the bottom of the jar. Now a long pipette was 

 partly filled with fresh clam juice, and the outside of it carefully 

 washed to remove all possible trace of clam odor from the surface of 

 the tube. When the lobsters were resting quietly the point of the 

 pipette was slowly lowered to the very bottom of the jar, where a few 

 drops of clam juice were liberated in the vicinity of the resting fourth- 

 stage lobsters. Within a few seconds all the larvse in that region rose 

 to the surface of the water, and swam wildly about for a variable length 

 of time. Then they again went to the bottom of the jar. Here they 

 either rested permanently, or, if a sufficient amount of the clam juice 

 remained near the bottom of the jar, the larvte, apparently restimu- 

 latecl, displayed further surface swimming. These same tests were 

 tried on the fifth-stage lobsters, but, although the clam juice might 

 excite them to more active crawling over the bottom of the jar, it 

 never produced the active surface swimming characteristic of the 

 fourth-stage lobsters under. similar conditions of stimulation. These 

 observations have received further support from facts which the 

 writer has learned from T. E. Emmel. It appeared in his experi- 

 ments that the hungry lobsters, when stimulated by a piece of clam 

 meat dropped into their confinement bottles, would not remain on 

 the bottom to enjoy the morsel, but would rise to the surface and 

 manifest active swimming for some moments. These few observa- 

 tions demonstrate clearly that the lobsters, at least of a certain age, 

 respond very definitely to certain kinds of food stimuli. To what 

 extent this kind of reaction may be responsible for the surface swim- 

 ming so characteristic of the early fourth-stage lobster under natural 

 conditions, it is difficult to say. It is not improbable, however, that, 

 after the fast that usually accompanies the approach of the third 

 molting process, the sense of hunger which characterizes the early 

 fourth-stage lobster may be in part the cause of the surface swim- 

 ming, although as has been shown in previous pages the reaction to 

 lisht is no doubt an influential factor. 



