574 
therefore must happen to be in some lone- 
some spot without other light, at the proper 
time of year, under the conditions noted above, 
and at least after 10 p.m. Even then his ob- 
servations unless published would not be likely 
to reach students. 
In Scrmncr for July 26, Dr. E. S. Morse 
gives a brief review of the subject,—with refer- 
ence to its meager literature. There we find 
mention of such conditions as “very warm 
and humid” a “profound calm” following 
a thunderstorm, “a small clearing” and 
“stumps ” or “trees.” 
The excessive abundance of fireflies at any 
one date is no doubt due to climatic condi- 
tions that have at first retarded and then 
hastened emergence from the pupa state. The 
fact that so many of these insects should 
occasionally be crowded into limited areas 
may be due to favorable ground conditions 
involving moisture; open spaces (where the 
light signal may be seen at a distance) ; favor- 
able places (trees, bushes, or stumps) for rests 
from flight;—shelter from winds;—and per- 
haps the antecedent direction and strength of 
such winds. The Valcour Island locality 
seems to fulfill these conditions and in ad- 
dition has a large sheltered area, the waters of 
the bay, across which the light may be seen 
but on which there is no resting place. 
Whether or not the flashes occur in strict 
unison and whether or not the sequence of re- 
curring responses is a measured one, and so 
strictly rhythmic, are questions which must be 
answered through more careful observation of 
the phenomena. Mr. Nylander, quoted by Dr. 
Morse, says “ The flashes were not so regular 
as an army officer would like to see in regi- 
mental drills but were so rhythmic that any 
one would take note of their action.” In other 
words, the concerted flashes did not recur with 
measured regularity but the repetitions were 
frequent enough to attract attention. How 
loose a meaning in this discussion do we wish 
to give the word “rhythm”? Dr. Morse 
quotes Mr. Purssell as stating “ To the best of 
my recollection the illuminated period lasted 
about two or three seconds and the dark period 
perhaps twice that long.” A space between 
SCIENCE 
[N. 8. Vou. XLVIII. No. 1249 
the beginning of one flash and the next which 
could vary from six to nine seconds would in 
no sense be rhythmic and even if the repeti- 
tions occurred with regularity, once every six 
seconds (the shortest time Mr. Purssell’s “ rec- 
ollection” allows), the rhythm would be in 
very slow, “largo” tempo. Note however in 
Mr. Morse’s quotation that the “ several thou- 
sand insects in each” of two trees “ perhaps a 
hundred feet apart,” “ flashed in synchronism. 
first one tree lighting up and then the other.” 
Here we haye the element of response which 
was so marked in the Valcour Island display. 
In the latter locality there were several trees 
and bushes on which rested groups which 
responded to each other and, at close range, 
the intervals between group flashings were 
usually but fractions of a second. The bril- 
liant blazing of the whole bank occurred at 
intervals varying from a few to many seconds 
in length—hence the similarity, when seen 
from a distance, to heat lighting. 
If it is desired to get a body of men to sing 
or play together in perfect rhythm they not 
only must have a leader but must be trained 
to follow such a leader. Imagine the diffi- 
culty of keeping together on “ Old Hundred ” 
if the notes were started with an interval so 
long as six or nine seconds between each. Do 
these insects inherit a sense of rhythm more 
perfect than our own? . 
Would not a more eritical observation of 
one of Mr. Purssell’s trees have shown him 
that one or more leaders started the flash and 
that the others “fell in” as in applause;— 
that the lighting of a tree gained at first in 
brilliancy and that the light also faded away 
gradually and not at once. At least this is 
what was noticed in the four different dis- 
plays on Valeour Island. 
We would ask observers to note the condi- 
tions resulting in such local congregations of 
these insects; to note critically whether the 
flashing are of the nature of exact unisons, or 
whether they spread out from small centers, 
first lighted, and so partake of a rapid but 
wave-like response to an initial stimulus; and 
to note also if the sequence of the flashings 
from the same group is one involving equal 
