NATURAI. HISTORY OF AMERICAN EOBSTER. 
359 
it would last 23 days, or a little over 3 weeks. Assuming that the bottom is not defin- 
itively sought until the close of the fifth stage, the free swimming life at Woods Hole 
would last 46 days, or a little over 6 weeks, and at Wickford about 30 days. 
Table 11. — Average Size and Duration op Stage Period in the First Eleven Stages. 
Assuming, further, that under natural conditions the molts are passed more rapidly, 
and that the bottom is sought some time between the close of the fourth and of the fifth 
stages, the pelagic life will be found to cover a period of from 3 to 4 weeks. 
CONDITIONS WHICH DETERMINE THE RATE OF GROWTH AND THE DURATION OF STAGES. 
The length of the stage period or the period between molts from first to last depends 
upon (i) intrinsic and (2) extrinsic causes. Among the intrinsic causes the following 
must be considered: (a) Inherited characters or the individual constitution, which 
gives a certain bent or direction to activities and limits their scope, and (b) acquired 
characters, such as the loss of limbs, which is certain to retard the rate of growth of the 
body as a whole by diverting energy to the regeneration of the lost parts. 
Thus if the fighting and preying instincts, due to inheritance, are stronger in larva 
A than in larva B, A will get more food, grow faster, molt sooner, and, its inherited cap- 
ital being equal in all other respects, it will distance B in the race from the start and, 
barring mishaps, forge ahead at every step of the way. The early advantages gained by 
A are cumulative in their effects. The parable of the talents is applicable even to the 
lobsters, and the laggard in the race, though of the same age, may not attain one-half, 
or even one-quarter, of the strength of its more strenuous rival, and will be fortunate 
if it is not cut into pieces and devoured, a contingency quite likely to happen when 
its running mates are crowded or underfed. 
Among the acquired characters are to be reckoned any weakness which may be due 
in the first instance to congenital defects, such as imperfect or undersized eggs, acci- 
dents like the loss of a limb, mutilations of any kind, which, as Emmel (90) has shown, 
increase the stage period and therefore diminish the rate of growth, or parasitism which 
may be encouraged by a lowered vitality or improper food. 
