210 Trans. Acad. Sct. of St. Lous 
ceived by the eyes. The light condition perceived by the eyes 
influences the moth to the activity of promiscuous flight by 
which he comes sooner or later into the odor stream of the fe- 
males. This odor is perceived by the organs of olfaction prob- 
ably situated in the antennae. Under natural conditions the 
sense of touch might assist in finally bringing the sexes to- 
gether, but this is only secondary, since I have seen males try- 
ing to mate with females inside a wire cage where contact was 
impossible. Sometimes the vibration of the female’s wings 
against the cage produces a musical sound, but in the open I 
doubt if they produce more than a vague rustling. No other 
evidence has at any time been observed which would indicate 
the functioning of auditory powers in the meeting of the sexes; 
nothing has indicated the presence of sounds outside the range 
of the ear of Man. This, then, reduces the number of senses in- 
volved in the coming together to two, seeing and smelling. We 
must not forget that without a condition of light to arouse the 
males to flight, and without wind to earry the odor which they 
follow in flight, there is no mating. 
Mayer thinks that the attraction of the male to the female 
promothea is due to chemotaxis. If following an odor trail to 
its source by hit or miss methods is chemotaxis, then the term 
may stand. If I walk along the street and catch a whiff of 
boiling sauer kraut, and poke my head into several restaurants 
until I find the one which stews the kraut, my action could 
hardly be called chemotaxis. If, however. you only saw me snif 
and enter the last restaurant without having seen me explore 
the others, you would interpret the behavior as chemotaxis. 
Mayer comes upon the scene and, finding males about his cages, 
he immediately says ‘‘chemotaxis’’; had he singled out num- 
bered or individual males, and with note-book in hand recorded 
their gyrations to and fro, up and down, in and around, leaving 
and returning, he would dispense with this term and simply 
describe the action as trial and error in response to odor. 
While Mayer and Soule say that the phenomenon which they 
witnessed in C. promethea and P. dispar, is chemotaxis, they 
surely do not mean to use the term in the sense of Loeb. 
They really mean finding the female by sense of yet for ber 
say: ‘‘frequently we have observed a male flying 
the wind until he passed by the side of and beyond the female, 
