NO. 10 



TROPISMS OF LEPIDOPTERA — McINDOO 



31 



was observed in the six instars. They are found widely distributed 

 (figs. 9 and 10) as isolated pores or " punctures " on the following 

 parts: Head capsule, 24; maxillae, 16; mandibles, 4; labrum, 2; 

 labium, 6 ; antennae, 2 ; legs, 30 ; first thoracic segment, 4 ; and anal 

 prolegs, 4 ; making 92 in all. Some of those on the head capsule were 

 incorrectly named in 1919 by the writer (51), but in figure 9 they are 

 correctly named according to Heinrich's (31) first paper and later 

 ones on this subject. 



In regard to experimental results concerning olfactory receptors, 

 two papers will be briefly reviewed. The first and most important 



Fig. 8. — Semidiagrammatic drawing of an oblique section through femur, tro- 

 chanter, and coxa of a silkworm moth, showing muscles (Mu), trachea (Tr), 

 nerves (iV), sense cells (Sc), sense hairs (St), and groups 8, 10, and 11 of 

 olfactory pores. No. 10 being shown partially from a superficial view; X 100. 



experimental work to decide the function of the olfactory pores was 

 done by the writer (48) on honeybees. Of the six sources of odors 

 used three were essential oils. The writer's critics have apparently 

 overlooked the fact that the results obtained by using the other three 

 odors are reported in such a manner that they can easily be considered 

 alone. Since the odors from the oils might have been irritant, let us 

 consider the other results, which, when expressed in percentages, 

 clearly show how closely the percentage of pores supposed to function 

 corresponds to the percentage of response obtained. On the average, a 

 worker honeybee has about 2,800 olfactory pores. On the bases of 

 the four wings lie 54 per cent of them; the legs possess 2^ per cent; 



