218 Trans. Acad. Sct. of St. Louis 
DISCUSSION OF RHYTHMIC PERIODICITY. 
Bouvier, in his already mentioned chapter on ‘‘Rhythms,’’ in 
agreeing with Loeb, says that in certain moths ‘‘This periodicity 
is independent of actual luminous stimulations.’’ To some ex- 
tent the experiments of Reaumur, whom he quotes, influences 
this decision. Reaumur says of moths enclosed in boxes and 
eages that during the day they are quiet in their prison, ‘‘pass- 
ing hours and often days without moving in the same place. 
But when night has come and even before the sun is set, they 
move their wings and fly as much as the box will permit.’”’ Of 
course this quotation seems contradictory inasmuch as they can- 
not spend days in their prison without moving and at the same 
time become active when night comes. What probably hap- 
pened with these moths was that some were placed in light-tight 
boxes, and these spent days without moving, while those which 
were in cages, where natural light could penetrate, responded 
to the dim rays of optimum intensity. By referring to our 
experiments, one can readily see that this is what happened in 
cynthia, cecropia and polyphemus. In tests in light-tight con- 
tainers, they did not move from their marked places for several 
days at a time, but became active only when dim light was ad- 
mitted. Obviously the statement that ‘‘ periodicity is independ- 
ent of actual luminous stimulations’’ does not hold for the above 
three species. Despite the fact that Reaumur’s statement, quoted 
above, gives us no assurance that his ‘‘boxes and cages’’ were 
light-proof, and hence there is nothing to show that the moths 
react in absolute darkness, Bouvier goes on to say that ‘‘this is 
a periodicity acquired by the organism. This is graven upon 
the being in the course of generations under the phototropic 
influence of periodical luminous stimulations and may show it- 
self today without their intervention. It has separated itself 
from the stimulating actions which have produced it.’’ 
Also from Loeb’s observations on the sphinx moth carried 
on ‘‘during two or three days,’’ Bouvier concludes: ‘‘Thus the 
periodicity appears to us to be manifest and independent of 
luminous variations.’’ But unfortunately, in the next para- 
graph, also based on the experiments of Reaumur and Loeb, he 
concludes: ‘‘Thus understood, the periodicity shows itself to 
be a simple manifestation of phototropism with these insects.” 
