REPORT OF COMMISSIONERS OF INLAND FISHERIES. 115 



ing bags in which from day to day the precious living larva) van- 

 ished from sight, and of the quarts of bright pink-colored dead speci- 

 mens mixed with dirt and silt and remnants of unused food that 

 came into view, when the bag was raised for inspection. In one of 

 the earlier experiments 5,000 handsome first-stage larva3, appropri- 

 ately designated from their condition the "gilt-edged lot," were 

 placed in a new scrim bag 12 feet square and about 4 feet deep and 

 were carefully tended. Out of the number only two individuals 

 came successfully through to the fourth stage. 



Light reactions. — As far as the movements of the larval lobsters are 

 not aimless, they seem to be directed mainly by responses to light 

 stimuli, and vary according to the intensity, color, and direction of 

 rays. They also seem to be modified, indirectly, by background. 

 Doctor Hadley in a study made at our station of the behavior of 

 lobsters observed that the character and responses bore a fairly con- 

 stant relation, not only to the stage, but to the period within the 

 stage. In cultural operations, where cars are used, the photopath- 

 ic responses of confined lobsters tend to bring them together into 

 close quarters, and are often therefore inimical because of the en- 

 couragement that this gives to cannibalism. In attempts to retain 

 the fry in ponds or small estuaries, these responses would very likely 

 tend to carry the lobsters to the shore to be entangled in the vegeta- 

 tion or stranded at the ebb tide. 



Parasites. — External parasites, including stalked protozoa, fungi, 

 diatoms, etc., are often a plague to the confined larvae. They grow 

 upon the shell and so encumber the larvae that feeding and moving 

 and breathing are difficult or impossible. Not infrequently, in fact, 

 the larvae are so completely covered with these foreign growths that 

 they can hardly be recognized. The parasities are got rid of at each 

 moult, but often they so weaken the larvae that moulting itself is 

 made impossible. The danger from this source is greatest when, by 

 reason of the low temperature of the water, the duration of the periods 

 between moults is increased. 



