ITS NERVOUS SYSTEM AND SENSE ORGANS. Ill 



genous cells. The number of grooves or pits may be enormous. 

 In the male of the Cockchafer, Hauser estimates that there are 

 39,000 in each antenna. He remarks that in all cases where 

 the female Insect is sluggish and prone to concealment, the 

 male has the antennae more largely developed than the female. 



Sense of Taste in Insects. 



F. Will* gives an account of many authors who have investi- 

 gated with more or less success the sense organs of various 

 Insects. He relates also the results of his own experiments, 

 and gives anatomical details of the sensory organs of the mouth 

 in various Hymenoptera. 



Wasps, flying at liberty, were allowed to visit and taste a 

 packet of powdered sugar. This was left undisturbed for some 

 hours, and then replaced by alum of the same appearance. The 

 Wasps attacked the alum, but soon indicated by droll move- 

 ments that they perceived the difference. They put their 

 tongues in and out and cleansed them from the ill-tasted powder. 

 Two persisted at the alum till they rolled on the table in agony, 

 but they soon recovered and flew away. In a few hours the 

 packet was quite deserted. After a day's interval, during 

 which the sugar lay in its usual place, powdered, and of course 

 perfectly tasteless, dolomite was substituted. The wasps licked 

 it diligently and could not be persuaded for a long time that it 

 could do nothing for them. Similar experiments were made 

 with other substances, and Insects whose antennao and palps 

 had been removed were subjected to trial. The result clearly 

 proved that a sense of taste existed, and that its seat is in the 

 mouth.')' Peculiar nerve-endings, such as Meinert and Forel 

 had previously found in Ants, were found in abundance on the 

 labium, the paraglossae, and the inner side of the maxillae of 

 the Wasp. Some lay in pits, through the bases of which single 

 nerves emerged, and swelled into bulbs, or passed into peculiar 

 conical sheaths. Interspersed among the gustatory nerve- 

 endings were setae of various kinds, some protective, some tactile, 

 and others intended to act as guiding-hairs for the saliva. 



* Zeits. f. wiss. Zool., 1885. 



t "Will confirms, by his owu experiments (p. 685), Plateau's conclusion (Supra, p. 46), 

 that the maxillary and labial palps have nothing to do with the choice of food. 



