RHYTHMIC NATURE OF ANIMALS AND PLANTS—BROWN 393 
4 a.m. Pacific standard time. In doing this we would still be follow- 
ing our 24-hour rhythm; this is, of course, 7 a.m., eastern standard 
time. But after a few days of experiencing the California social and 
day-night rhythms, we would have reset our rhythm to Pacific stand- 
ard time and would have the same kind of experience, but now in 
reverse, were we to fly back to New England. 
The foregoing is an example of a fundamental property of rhythms 
of living things which has given biologists more information. My 
associates and I performed an objective experiment of this nature 
with fiddler crabs a few years ago. Crabs, which were changing 
color in a darkroom in our laboratory on Cape Cod, Mass., at the 
usual times, dawn and dusk, were divided into two equal-sized batches 
and sealed in lightproof cartons. One batch was carried by airplane 
to be opened in an experimental darkroom at the University of Cali- 
fornia the next day. Synchronously, by prearrangement, the other 
group was opened in a darkroom on Cape Cod. The rhythms of color 
change in the two lots of crabs on the two sides of the continent was 
studied. The times of darkening and lightening for the two batches 
were carefully compared. Both were on eastern standard time. The 
crabs that had traveled to California kept their rhythm on eastern 
standard time, both during the trip and during the 6 days in Cali- 
fornia that they could be studied. The average time difference for 
the 6-day period was only 12 minutes; this was within the error of our 
measurements. The crabs showed no tendency to shift their rhythms 
to accord with the dawn and dusk of California. 
From this last experiment it was possible to draw certain conclu- 
sions. (1) Since, during the day of their westward trip, the crabs had 
been subjected to an artificial day of 27 hours and 20 minutes with 
respect to any and every “local time” factor that possessed its 24-hour 
period as a consequence of the rotation of the earth relative to the sun, 
the crabs clearly could measure one 24-hour period without any kind 
of clue, even a subtle one, of this nature. (2) Once in California where 
rhythms of many physical environmental factors were once again 
24-hour ones, the crabs could retain an accurate 24-hour rhythm in a 
new time relationship relative to the external ones. (3) To reset their 
rhythms to Pacific time, the crabs needed exposure to one or more 
natural California light cycles. 
The year following this study on the crabs, a completely comparable 
experiment was performed by Renner, using the time sense of honey 
bees. Completely duplicate bee-training rooms were built and fur- 
nished in Paris and in New York. Bees were trained to come to a 
particular spot in the Paris room for food at a particular time of day. 
Once trained, the bees were sealed in a container and flown to the room 
in New York. The bees, now in New York, came to the feeding spot 
