HYMENOPTERA. 



27 



organs described by Wolff there is no doubt, and 

 their position certainly seems to indicate that they 

 are organs of taste. Moreover, we are not, I think, 

 sufficiently acquainted either with the essential 

 requisites of an organ of taste, on the one hand, or, on 

 the other, with the minute structure of these organs, to 

 feel justified in concluding that this is impossible. It 

 must be remembered that these pits are very minute, 

 being only from •003 to "006 of a millimetre in diameter, 

 so that it is hazardous to assert that they are certainly 

 imperforate, while even if they are, 

 this would not necessarily prove 

 that they cannot be organs of taste. 



Fig. 26 shows three of Wolff's 

 cups, each with a central hair, a 

 chitinous ring, and a double gan- 

 glionic swelling terminating in a 

 nerve-fibre, magnified 500 times. 



An additional reason for sup- 

 posing that the Wolffian pits are 

 really sense-organs arises from the 

 fact that they are fewest in those 

 insects which we may reasonably 

 suppose to have the sense of taste least developed, 

 and increase in number where, on other grounds, we 

 may fairly regard it as being probably more highly 

 developed. Thus the Chalcididse have often only one 

 or two; the Evaneadse, seven; the Proctotrupidfe, 

 fifteen ; the Tenthredos, twelve to twenty-four ; the 

 common wasp, twenty : some of the great tropical wasps, 

 forty ; while in the hive bee, the drone has fifty, the 

 queen about one hundred, and the worker rather more 

 still, say one hundred and ten. 



Fig. 26. — Shows three of 

 Wolff's cups, each with a 

 central hair, a chitinous 

 ring, and a double gangli- 

 onic swelling terminating 

 in a nerve-tibre, x 500 

 times. B, R', Sensory pits 

 and hairs; G. (J, ganglionic 

 swelling of nerve. 



