1927] Olfactory Function of the Antennae of Insects 213 
copper screen, producing two compartments, one for the roaches 
the other empty. The roaches were then held for two days to 
permit the operated ones to recover from the effects of the am- 
putation. During this time they were given nothing but water 
in order to create an intense hunger. On the second day the 
insects seemed perfectly normal and a small piece of Roquefort 
cheese, for which these animals manifest a great fondness, 
was placed in the empty compartment one inch from the copper 
screen. In a few seconds the normal insects, which were huddled 
in a far dark corner, began to move their antennae and within 
two or three minutes one began to move over towards that part 
of the screen from which the cheese odor emanated. This one 
waved his antennae about near the cheese, but not being able to 
touch it soon returned to the corner. A little later the other 
roach followed the same maneuver. Both insects repeated this 
behavior three to four times. During the entire length of these 
operations, the roaches with amputated antennae gave no res- 
ponse and when they moved they progressed along the side op- 
posite the cheese which happened to be the darker side. During 
these tests both cages were held in the same position and at the 
same distance from the source of light. The cheese and the 
roaches were then removed and the cages washed thoroughly to 
remove all odors. 
In a few days the roaches were again placed in their res- 
pective cages, and after the animals had been starved again for 
two days some Roquefort cheese was smeared on each cork 
plugging the hole of the compartment containing the insects. 
Within one to two minutes the normal roaches ran over to the 
soiled cork and ate off the cheese. The roaches with amputated 
antennae did not respond. After more than two hours they 
finally came across the cheese, waved their palpi and ate. It 
seems that the antennae receive smell impressions at considerable 
distances and that the maxillary and labial palps can only per- 
ceive an odor when the insects are in close proximity to the 
volatile substance. The antennae, maxillary and labial palpi 
were removed from another group of roaches. After recovery 
from the operation, and after the customary starvation, they 
had even greater difficulty in finding the cheese than those 
