proceedings: entomological, society 527 



The recording secretary made a statement regarding the importance 

 of speakers furnishing him with abstracts of their remarks and an- 

 nounced that hereafter speakers will be furnished with blank forms for 

 abstracts 



New member: Edward A. Chapin of the Biological Survey. 



The regular program was as follows: 



N. E. McIndoo: The olfactory sense in Orihoptera. In making a 

 comparative study of the disposition of the olfactory pores in Orthoptera, 

 both sexes of 21 species belonging to 20 genera and representing the 

 6 families were examined. Olfactory pores are more widely distributed 

 in Orthoptera than in any of the higher orders of insects. They are 

 always found on the legs, antennae, and anal stylets; usually on the 

 wings (if present), abdominal segments, cerci, head, and all the mouth- 

 parts; and sometimes on the thoracic segments and ovipositor. Rel- 

 ative to the antennae a few usually lie on the first segment, but always 

 many on the second segment. In regard to the total number of pores 

 found, mantids and phasmids have the smallest number, certain acridids 

 have the largest number, while the remaining species have a median 

 number of about 1000. The newly hatched croton bug has 44.5 per 

 cent as many pores as the adult female, and also the pores in the six 

 instars of the grasshoppers gradually increase from 46 per cent in 

 the first instar to 100 per cent in the adult female. Externally these 

 organs are usually oblong, sometimes almost slit-shaped, but the eye- 

 shaped type is the most common. Internally each one has a spindle- 

 shaped sense-cell whose peripheral end unites with the pore aperture 

 in the chitin, thus allowing the external air to come into direct contact 

 with the nerve. Experiments were performed on grasshoppers and 

 crickets to determine whether the so-called olfactory organs on the 

 antennae receive olfactory stimuli. Since the antennae were cut off 

 just distal to the olfactory^ pores on the first and second segments it 

 appears from the reaction times obtained that the remainder of the 

 antennal segments, which bear the so-called olfactory organs, do not 

 serve as an olfactory receptor as other investigators claim. 



In answer to questions by various members. Dr. McIndoo stated 

 it as his belief that the antennal organs commonly supposed to be 

 olfactory are tactile, and serve for the detection of air currents; that 

 evidence of the olfactory nature of the organs he had discussed was 

 obtained by removal of appendages and painting over the other organs 

 with beeswax and vaseline; and that in order to eliminate the element 

 of shock he had delayed his experiments for 24 hours after mutilation. 

 ISIr. MiDDLETON questioned Dr. McIndoo on whether all the types 

 of organs represented (those he interpreted as olfactory and those 

 believed by others to furnish insects with that sense) were found mixed 

 together in the same locality or cluster, suggesting that if not, by elimi- 

 nating certain types of organs by coating those portions of the body wall 

 containing them, the true organs might be determined and that 

 some further information on the constitution of an odor might be 



