Summary and Discussion 215 
table.’”’ Unfortunately, he has no actual knowledge of whence 
they came or how far. Because he suspects that they travel very 
great distances, so great in fact that he cannot conceive that 
odors can travel so far, he tries to account for the behavior in 
new and mysterious ways, for he says: ‘‘Like light, odor has its 
X-rays. Should science one day, instructed by the insect, en- 
dow us with a radiograph of smells, this artificial nose will open 
out to us a world of marvels.’’ 
No new device now seems needed to open up a new world of 
marvels in this instance. My investigations show clearly that 
there is a limit to the distance males can travel to reach the 
females. The further away from the females they are liberated, 
the fewer will return. Fewer will return from three miles than 
from a.half-mile, and those which do make the long distance are 
exceptional individuals. Without wind bearing the female odor 
there would be no attraction of the males. It is easy for me to 
believe this, since I have myself repeatedly caught whiffs of 
cecropia odor on the breeze, although my olfactory organs are 
not especially attuned to these emanations. O. W. Richards* in 
speaking of Mayer’s work on Callosamia promethea, makes this 
very pertinent remark: ‘‘The distance that males are attracted 
is probably often exaggerated and, in this connection it must be 
remembered that the males of these forms have often a very 
erratic flight, coursing about in all directions.’’ I judge, from 
observations in the laboratory, that they are inactive until the 
time for flight, and then fly at random until they find an odor 
trail 
Fabre and others constantly remind us that there is no sim- 
ilarity between our sense of olfaction and that of the insects, but 
Belloncif finds, in studying in a comparative way the olfactory 
lobe of the lower vertebrates and the antennary lobe of insects, 
that the histological structures of these organs in the arthropoda 
have a very close relation to that of the olfactory lobe of verte- 
brates, and concludes therefrom a physiological if not a mor- 
phological homology. Forel is willing to admit ‘‘that the olfae- 
tory bulb and the nasal mucuous membrane of the vertebrates 
are derived from the invagination of the antenna and the an- 
peaeary ganglion of an invertebrate. The nerve terminations, 
a. Reviews 2:320. 1927. 
+Cited by Forel, Senses of Insects, p. 96. 
