NO. 10 



TROPISMS OF LEPIDOPTERA — McINDOO 



35 



through the intima when the latter is wet on both sides. From this 

 result he concluded that the olfactory organs of insects need no 

 openings through which the nerve endings can come in contact with 

 the odorous air outside. The present writer cannot see any connection 

 between his findings and the chemical sense receptors of insects. 



Fig. 12. — Olfactory and gustatory organs of higher animals. A, Diagram of a 

 block from olfactory mucous membrane of a kitten, showing in section and per- 

 spective the following: Basal cells (b), olfactory cilia (c), nerve fibers (/), 

 limiting membrane (/), olfactory cells (o), supporting cells (s), olfactory 

 vesicles (v), and walls (w) of the five- and six-sided supporting cells from a 

 surface view. The olfactory vesicles and cilia, which are embedded in and sup- 

 ported by an outer semifluid (not shown in drawing), are the true receptors of 

 smell. (Redrawn from van der Stricht's (84) photomicrographs and figure 36, 

 the latter in Herrick's book (33).) B, A single taste-bud from human tongue, 

 showing nerve fibers (/) indirectly innervating the surrounding epithelium (e), 

 supporting cells (s), and taste cells (t), whose outer ends project into and 

 sometimes beyond the pore (/>). (From Herrick (33), after Markel-Henle.) 



2. SO-CALLED TASTE ORGANS 



The so-called taste organs of Lepidoptera, according to Deegener's 

 review (see Schroder (80) p. 149), consist of two round groups of 

 sense hairs on the under side of the pharynx. The proboscides of 

 Rhopalocera, Noctuidae, Geometridae, and Bombycidae bear at their 

 tips more or less numerous peg-shaped structures of varied lengths 

 and shapes in different species. In Sphingidae and Zygaenidae these 

 pegs are distributed over the entire proboscides. These peculiar 



