460 
perature. The nuclear changes are similar to 
those found in Paramecium. A large percentage 
of exconjugants usually die, but sometimes all 
live. The proportion of fatalities is essentially 
the same in small individuals taken from the 
same culture but not allowed to conjugate, while 
large individuals nearly all live. There is no evi- 
dence indicating that there is any difference in 
the vitality of the two individuals of conjugating 
pairs foreshadowing sexual differentiation, as held 
by some investigators. The rate of fission is ap- 
parently not affected by conjugation, and if there 
is a rhythm in the rate of division, such as has 
been described for certain other infusoria, it is 
independent of conjugation as is shown by the 
following results. In seven closely related fam- 
ilies under the same environmental conditions the 
rate of fission was practically the same during a 
period of several weeks, although the number of 
generations since conjugation at the close of the 
experiment varied in the different families from 
123 to 553. Conjugation is almost invariably ac- 
companied by encystment, 7. e., when certain indi- 
viduals in a culture conjugate others encyst. This 
seems to indicate that conjugation, like encystment, 
functions in bridging over periods of unfavorable 
environmental conditions. Conjugation produces 
an increase in physiological variability; some of 
the exconjugants consequently have a better 
chance to survive under adverse conditions than 
do those which have not conjugated. 
Behavior of Fire-flies (Photinus ardens?) with 
special Reference to the Problem of Orienta- 
tion: S. O. Mast, Johns Hopkins University. 
The fire-flies studied are found in dark crevices 
or under ground during the day. In the evening 
when it is still light enough to read they come 
out; the females crawl to the tips of grass or 
other objects and remain quiet; the males fly 
about and glow fairly regularly at intervals of 
about five seconds. The females do not glow 
unless light from the males or from some other 
source is flashed on them. When a female glows 
in response to the glow of a male, the male ordi- 
narily turns directly toward her. This is repeated 
until the two come together, after which copula- 
tion takes place. There are no other factors in- 
volved in mating. If a female is held near a male 
he pays no attention to her unless there is actual 
contact, showing that neither objective vision nor 
smell is functional in mating. The males do not 
orient when exposed to continuous illumination. 
They respond only to flashes of light, and do not 
SCIENCE 
[N.S. Vou. XXXV. No. 899 
react until after the light has disappeared. Thus 
orientation may take place in total darkness, and 
it is surprising how accurately these animals turn 
through the proper angle in the total absence of 
the stimulating agent that caused the response. 
Here we have a case in which it is clearly demon- 
strated that light does not act continuously in the 
process of orientation as demanded by Loeb’s 
theories, a case in which it is also clearly demon- 
strated that continuous stimulation is not neces- 
sary to keep the organism oriented. 
Expermients with the Influence of Darkness wpon 
Pigment Development in Amphibian Larve: 
A. M. Banta, Station for Experimental Evolu- 
tion. 
From newly laid eggs series of Amblystoma 
tigrinum were reared (1) in darkness and (2) 
in ordinary laboratory light, and compared 
with those developing (3) in the pool where 
the eggs were laid. The amount of pigment 
developed in each individual of the different 
series was determined by means of color tops, and 
records were made in terms of the percentages of 
black, white, orange and yellow, which when 
blended matched the color of the animal’s skin, 
For the salamanders on the average the body color 
of the series reared in darkness contained 49.7 
per cent. black and 50.3 per cent. non-black (16.9 
white, 9.3 orange and 24.1 yellow); the series 
reared in laboratory light averaged 86.1 black and 
13.9 non-black (4.7 white, 2.4 orange and 6.8 
yellow); and the series examined from the out- 
door pool averaged 86.6 black and 13.4 non-black 
(4.5 white, 3.1 orange and 5.8 yellow). Hence the 
salamanders reared in darkness contained about 
four times as much non-black in the body color as 
those reared in daylight in the laboratory or in 
the outdoor pool where the eggs were laid. The 
darkest individual in the series reared in darkness, 
with 70.5 black, was much lighter than the lightest, 
with 82 black, of either of the series reared in the 
light. 
To be published in full in The American Nat- 
uralist. 
A Comparison of the Light Reactions of a Sub- 
terranean and an Epigeal Race of an Amphipod 
Species: A. M. Banta, Station for Experimental 
Evolution. 
The Spawning Habits of the Sea Lamprey, Petro- 
myzon marinus: L. Hussakor, American Mu- 
seum of Natural History. 
The observations were made on the Nissequogue 
River at Smithtown, Long Island, June 1 and 2, 
