188 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Surface towing was done at the following places in the same year without obtain- 
ing any lobsters: August 1, 17, and IS, Vineyard Sound; August 23, off Cuttyhunk; 
August 27, 30, 31, Woods Hole Harbor. 
Professor S. I. Smith says of the young lobsters which he obtained in Vineyard 
Sound in the summer of 1871, that numerous specimens “were mostly taken at the 
surface in the daytime, either with the towing or hand net” {182). Of the older pelagic 
stages he says: 
They appear to live a large part of the time at the surface, as in the earlier stages, and were often 
seen swimming about among the surface animals. They were frequently taken from the 8tli to the 28th 
of July, and very likely occur much later. 1 
We know that lobsters are now far less abundant around the Elizabeth Islands 
than they were twenty years ago, and we should expect to find that the young had 
diminished in a proportionate degree. Millions of larvae, however, must still be 
hatched in Vineyard Sound and adjacent waters every year. What then becomes of 
them? I believe that they are eaten up by surface-feeding animals, principally lish, 
or meet their death from indiscriminate causes. The tides tend to disperse the young- 
over a wide area, thus carrying them to and from the shores. Horizontal distribution 
alone would not account for the extreme scarcity of the young in Vineyard Sound at 
the present time. If, however, there were a corresponding vertical distribution, the 
conclusion which we have reached would not be warranted. It thus becomes a matter 
of much interest to determine the heliotropism of the larvae, or the law which governs 
their vertical movements in the water. 
The results of my observations and experiments with larvae lead me to conclude 
that the young, free-swimming lobster usually displays what Loeb has called positive 
heliotropism {125 ) — that is, it tends to swim toward the light or uear the surface in the 
daytime. The conclusion therefore which we stated above, that the absence or extreme 
scarcity of young lobsters in a region where the adults still abo und is due to their destruc- 
tion , is supported by experimental testimony. The bearing of this fact upon the artificial 
propagation of lobsters I have discussed in an earlier paper (see .97). 
I will add a few notes upon the experiments which were made to test the helio- 
tropism of these larvae. 
Experiment 1 . — On June 27, 1894, I placed about 25,000 young lobsters, in the first 
larval stage, in the observation pool at the Fish Commission Station, to watch their 
behavior. The sun was intermittently obscured by clouds during the greater part 
of the forenoon. When liberated, the larvae formed a large cluster near the surface, 
where they remained for a short time. Then all went down to a distance of from 1 
to 2 feet, some apparently reaching the bottom, a distance of 3 feet more. A lot of small 
‘With reference to this subject, Professor Smith has kindly written in detail substantially as 
follows: “All the larvae captured in Vineyard Sound and neighborhood in 1871, on which my papers 
were based, were taken in the ‘daytime.’ My notes usually give only ‘day,’ or ‘evening’ for time 
of capture, but the larvae of my first and second stages, taken July 1, are marked ‘forenoon.’ 
Since 1871 I have many records of first and second stages taken in the ‘day’ and, as far as I can find 
now, only two cases of capture in the ‘evening,’ and one of these cases was when the electric light 
was used in the water to attract the surface forms. The young in the adult form [equivalent to fourth 
and possibly fifth and sixth stages described in this work] were, however, often taken in the evening 
aud were almost always attracted by the electric light. In my experience the young of the adult 
form were much more frequently taken at the surface than the larvae.” 
