THE AMERICAN LOBSTER. 
225 
molt rudimentary abdominal appendages appear on the second to fifth abdominal 
somites, inclusive, and the branchial formula is completed. 
(56) At the fourth molt it loses the use of its larval swimming organs, but still 
remains at the surface, propelling itself forward by its swimmerets and backward by 
flexion of the abdomen. It is now from three to four weeks old, is half an inch long, 
and has characteristic colors. 
(57) After the fifth molt is passed the young lobster still swims at the surface, 
though it is possible that some leave it during this stage. When the sixth stage is 
reached, age five to six or eight weeks, length about three-fourths of an inch, it remains 
at the surface for a time at least, but goes to the bottom to stay before the seventh 
molt is passed. At the sixth molt all trace of the larval swimming organs is lost. 
(58) The molts follow each other at rather short intervals, and during the first 
year of life, supposing the animal to have been hatched in June, the lobster molts 
from fourteen to seventeen times and attains a length of from 2 to 3 inches. The 
main facts of the subsequent life-history need not be repeated. 
(59) The problem of artificial propagation of the lobster will be solved when 
means are devised by which the larvie after hatching can be reared in large inclosures 
until the fifth or sixth stage, when they are able to take care of themselves. 
(60) Food of larvae . — The food of the larval lobster consists of minute pelagic 
organisms of all kinds. They show little discrimination at this time, snapping up any 
floating objects not too large for them to manage. 
(61) Heliotropism of larvae . — In the pelagic stages the young lobsters are positively 
heliotropic, rising to the surface in the daytime and staying there, and going down at 
night. This habit is not invariable, but the capture of the young by day is the rule, 
by night the exception. 
(62) Survival of larvae . — Great destruction is wrought upon the free-swimming 
stages by both animate and inanimate enemies. A survival of 2 in every 10,000 
larvae hatched would maintain the species at an equilibrium, and the destruction of 
the young under the present conditions of the fishery is probably even greater than 
this implies. (For a discussion of this subject see No. 97 of Bibliography.) 
(63) The general scarcity of the young in the hatching season in places known to 
abound in lobsters is due (1) to their wide horizontal distribution, and (2) to their 
destruction. 
(64) The whole course of development and later growth is slow. The slow larval 
development secures the necessary transportation from the shores and wide horizontal 
distribution, which is absolutely necessary for the life of the species. An abbreviated 
metamorphosis such as is found in this animal appears to be a compromise between a 
still longer development which the animal would have to go through if the egg 
possessed less yolk, and the limitations to protoplasmic activity which are imposed by 
the temperature of the North Atlantic Ocean. 
For the facts pertaining to the development of the embryo the reader must refer 
to Chapter xm, and for details and the discussion of general questions to the body 
of the work. 
F. e. B. 1895—15 
