A METHOD OF LOBSTER CULTURE. 227 
earlier experiments 5,000 handsome first-stage larve, appropriately 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 constant relation, not only to the stage, but to the period 
within the stage. In cultural operations, where cars are used, the photopathic 
responses of confined lobsters tend to bring them together into close quarters 
and are often therefore inimical because of the encouragement that this gives 
to cannibalism. In attempts to retain the fry in pounds or small estuaries, 
these responses would very likely tend to carry the lobsters to the shore, to be 
entangled in the vegetation or stranded at the ebb tide. 
Parasites —External parasites, including stalked protozoa, fungi, diatoms, 
etc., are often a plague to the confined larve. They grow upon the shell and 
so encumber the larve that feeding and moving and breathing also are 
difficult or impossible. Not infrequently, in fact, the larve are so completely 
covered with these foreign growths that they can hardly be recognized. The 
parasites are got rid of at each moult, but often they so weaken the larve 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. 
Food.—Not the least of the difficulties connected with rearing lobster 
fry is the providing of proper and available food. In small experiments the 
live copepods and other pelagic food natural to the lobsters in these stages can 
be supplied, but on a large scale this is not an easy matter. Naturally, food 
that sinks to the bottom can not be reached by fry that normally swim or 
float. 
Requisites of water, etc—The foregoing facts regarding the characteristics 
of the fry in general and the peculiarities which they manifest when in con- 
finement have to be taken into consideration in any attempt to rear the lobster 
through the critical period of its life. To these considerations must also be 
added the important question of an adequate supply of water, uncontaminated 
by chemical or bacterial impurities, constantly furnished with the proper 
amount of oxygen, and sufficiently free from injurious gases arising from the 
metabolism of animal or bacterial content. Finally, in any method of lobster 
culture there must be taken into consideration its practicability when applied 
on a large scale and its feasibility with regard to the cost of operating. 
