92 THE AMERICAN NATURALIST. [VOL. XXXII. 
the lowest for the day. From this time on the bees returned 
in large numbers evidently, and the hive consequently rose in 
weight, so that it passed the zero line at 7 o’clock, and reached 
150 gm. above the morning weight one hour later, when the 
weighing was discontinued. This 150 gm. of course represents 
the amount of stores secured during the day. 
The most remarkable feature of this curve is the sharp rise 
just before noon, thus making two points of minimum weight 
for the day. Several suggestions might be made to explain 
this peculiarity. Directly, it is certainly due to a large number 
of bees returning at about the same time. The small amount 
of honey gathered and stored during the day seems to indicate 
some relation with the nectar flow, which evidently was not 
great. Dufour, basing his remarks on experiments by Bonnier, 
explains the matter by pointing out that the flow of nectar 
varies during the day, and has a forenoon and an afternoon 
maximum flow, with an intervening period of small flow. 
According to these experiments, the nectar flows freely during 
the cooler portions of the day and much less so during the 
period of greatest heat, which ordinarily comes somewhat after 
midday. Of this change in the nectar flow the bees take 
advantage, and the peculiar curve which has been described is 
aresult. This explanation is not, however, sufficient to account 
for the rise in this particular curve at 11 o'clock, for the reason 
that, as noted above, the hottest part of the day does not 
ordinarily occur in the forenoon. It seems, however, to explain 
the curve of July 20, where the intermediate rise reaches its 
maximum at 2.30. The difference between the two curves in 
respect to this rise may doubtless be explained by the difference 
in the total flow of nectar, which a comparison of the two 
curves shows to have been very much greater on July 20. The 
flow being small on May 8, it would consequently soon be 
exhausted, causing the bees to return earlier than they would 
have done had it been more abundant. 
By May 18 conditions had evidently very materially changed. 
During the first one and one-half hours the bees left the hive 
slowly, although somewhat more rapidly than during the corre- 
sponding time on May 8. From a little after 7 o’clock they left 
