THE OLFACTOEY SENSE OF ORTHOPTERA 423 



Child saw the olfactory pores, described by the present writer, 

 but he did not make a study of them; he soon decided, however, 

 that they did not belong to the Johnston's type and did nothing 

 further with them. 



RESPONSES TO CHEMICAL STIMULI 



In table 1 it is shown that an adult male or female (no. 16 or 

 17) of Melanoplus femur-rubrum has about 1500 olfactory pores, 

 108 of which lie on the second antennal segments; also, that an 

 adult male or female (no. 44 or 45) of Gryllus pennsylvanicus 

 has over 1000 pores, 75 of which lie on the second antennal seg- 

 ments. Using a pair of fine-pointed scissors, it was ascertained 

 that the antennae could be cut off not nearer the head than 

 through the third segments, therefore, five normal males and 

 five females of each of the preceding species were selected for 

 experimental purposes. Before mutilating them each one was 

 placed in an experimental wire-screen case and was tested with 

 the following sources of odors: chemically pure oils of pepper- 

 mint, thyme, wintergreen and lemon, dried leaves of pennyroyal 

 (odor very weak), and bran mash. The bran mash was made 

 by using wheat bran, cheap molasses, lemons cut into fine pieces, 

 and water; this mixture with arsenic added is the well-known 

 poisoned bran mash, used for the control of grasshoppers, which 

 are very fond of it either in the fields or in captivity, but crickets 

 prefer bread or certain fruits to it. 



Experiments with grasshoppers (Melanoplus femur-rubrum) 



The following records include only the first responses and their 

 reaction times: 



a. Unmutilated grasshoppers. These individuals were appar- 

 ently normal in all respects. 

 Oil of peppermint: 



3 moved body slightly. 



2 raised front legs. 



2 moved backward slowly. 



1 raised hind leg and turned around slowly. 



THE JOURNAL OF COMPARATIVE NECROLOGY, VOL. 31, NO. 5 



