1927] Olfactory Function of the Antennae of Insects 211 
Mclndoo (13) entirely discards the view that the antennae 
function as olfactory organs. This investigator has done much 
work on this subject and has experimented chiefly with beetles, 
bees and ants. Mclndoo considers the abnormal behavior of 
insects towards odor when the antennae are amputated, but 
thinks this is due to the fact that such insects are abnormal in 
their whole behavior. This is, of course, contrary to von Frisch’s 
careful experiments and, if true, would apply equally to Mcln- 
doo’s own work. Any animal that has been deprived of a sense 
organ will react abnormally with respect to a stimulation that 
affects this particular organ. Mclndoo finds that olfactory pores 
exist in other regions of the body, especially at the bases of the 
wings and legs. When these pores are varnished over the insects 
respond much more slowly to odors than do those whose antennae 
are amputated. Kennedy (14) recently carefully weighed the 
evidence for and against the antennal sense of smell and thinks 
that while olfactory receptors undoubtedly do occur on other 
parts of the body, the experimental evidence against the older 
theory of an antennal sense of smell is insufficient. Judging 
from the literature, it seems that much substantial evidence 
exists in favor of the older theory. However, since roaches are 
exceedingly favorable material for a study of this question and 
furnish another rather lucid illustration in support of the older 
view, the writer feels prompted to report some observations. 
2. Observations and Experiments on Periplaneta americana. 
Periplaneta americana , the large American roach, carries two 
extremely long antennae on which occur the so-called olfactory 
cones. The maxillary and labial palpi of this species also bear 
sense organs which were, likewise, considered by Graber to 
function in the detection of odors. It was noticed by us that the 
antennae of starved roaches moved continuously when some 
odorous food was tendered but held at a distance to prevent 
contact. This then led to the performance of some further ex- 
periments which would demonstrate whether the antennae har- 
bored chemoreceptors. Full grown male and female roaches 
were placed in an atmosphere containing a slight amount of 
ether vapor. After a minute or two the insects began to behave 
