150 
Psyche 
[October 
gleich 3 Hummeln auf einmal aus dem Nestloch, nachdem mit 
Korbchen beladene im Tor vorher einpassiert waren und der 
Betrieb in der Hummelburg kommt in regen Gang.’’ 
These two passages would not have been written, had Bach ' 
mann (1915, 1916) paid more attention to the literature of the 
preceding decade. As we have already seen, Bachmann’s (1915> 
1916) assertions were contradicted years before, by statements 
published by several authors, notably von Buttel-Reepen (1903), 
Lie-Pettersen (1906), Wagner (1907), Lindhard (1912), and. 
Sladen (1912). To these may be added certain observations 
and experiments of my own. 
During the summers of 1921 and 1922, I had under obser- 
vation about sixty Bremus (Bombus) colonies belonging to teiP 
of our thirteen New England species, and have frequently had 
occasion to observe the behavior which gave rise to the ‘trump- 
eter” story. That the fanning of these so-called trumpeters has 
to do with ventilation of the nest, and not with rousing the 
colony, or the exercising of wing muscles, may be demonstrated 
very easily by exposing a bumblebee colony to the rays of the 
sun, a fact which was first pointed out by Lie-Pettersen (1906) 
and Wagner (1907). The conclusions which these two authors 
reached are corroborated by the following observations which 
were made during the summer of 1921. 
Of the thirteen colonies which I had under observation 
during that summer, eleven were kept in windows facing south 
and the remaining two in a window which faced north. Like 
Lie-Pettersen (p. 18), I found that on every warm day, especially 
if the weather was sultry, one or more workers in each of the 
colonies on the south side of the building mounted to the top of 
the nest and began to fan shortl}^ after the rays of the sun reached 
the nest-boxes. In a colony of Bremus impatiens, consisting of 
about 125 individuals, the number of fanning workers sometimes 
even increased to more than a dozen. As soon as the sun receded 
from their nest-box, these “trumpeters” discontinued their work, 
one after another, and crawled back into the nest. 
^Bremus affinis, bimaculatus, fervidus, impaliens, pennsylvanicus , per plexus, separaius, 
ternarius, terricola , and vagans. 
