ORGANS OP TASTE IN INSECTS. 25 



mouth or its immediate neighbourhood ; and in all the 

 orders of insects there are found on the tongue, the 

 maxillae, and in the mouth, certain minute pits which 

 are probably the organs of taste. In each pit is a 

 minute hair, or rod, which is probably perforated at 

 the end. On this point there is, indeed, some dif- 

 ference of opinion. Will, for instance, maintains 

 that to convey the sense of taste the food must come 

 into direct contact with the termination of the nerve 

 of taste, so that those hairs, or bristles, on the mouth 

 parts which present no perforation cannot be regarded 

 as true taste-organs, and probably serve rather as 

 guards. Forel, on the contrary, considers this as an 

 error. He observes, with justice, that the secretions 

 are able to pass through the chitinous membrane 

 which terminates the excretory canals of the glandular 

 cells, and he maintains that the chitin is so thin 

 and delicate — as well on the surface of the taste cones 

 and hairs as on the olfactory hairs and plates of the 

 antennae of bees and other insects — that endosmosis 

 through this fine membrane may sufficiently explain 

 the sensation. 



In 1860 Meinert * described, on the maxillae and 

 tongue of ants, a series of chitinous canals, connected 

 with ganglion cells, and through them with the nerves, 

 and suggested — though with a note of interrogation — 

 that they might be the organs of taste. Forel, in 1874, 

 confirmed these observations of Meinert's, and described, 

 at the point of the tongue of Formica pratensis, a series 

 of seven such chitinous tubes. In the following year 

 Wolff published his work, "Das Riechorgan der Biene," 

 which contains a number of valuable observations, 



• " Bid. til. de Danske Myrers Natur Hist." 1860. 



