296 



Mr. Nunney read a note " On certain Discs found on the 

 Stigmal Veins of a Chalcid Fly." 



Mr. Ingpen said that the specimens were amongst a number 

 of insects he received some time ago as examples of iridescence. 

 He was rather struck by the appearance of these discs, and the 

 question was suggested whether there was a nerve connected 

 with, them, and if so what was its character. It seemed to him 

 that there was a well-developed nerve there, and he thought 

 there could be little doubt that so large a nerve would have 

 some important function beyond that of merely supporting the 

 framework. 



Mr. A. D. Michael said it was difficult to say anything about 

 a thing which, he had not had any opportunity of examining. 

 It was, however, well known that there existed a more or less 

 vibratile disc within the stigma, and that this being more or less 

 in the air passage was supposed to be capable of closing the 

 stigma ; and he did not know that there was any inherent im- 

 possibility in there being an auditory organ in such a position. 

 It would also appear to follow that if the vibratile disc was con- 

 stantly in use the nerve would be large. It was, however, very 

 important to see if the nerve ended in a nerve terminal, for only 

 this would give the impression that it was a sense organ. It 

 was quite possible that it was one, and that these vibratile 

 discs had the function of closing the stigma on fitting 

 occasions. 



The thanks of the meeting were voted to Mr. Nunney for 

 his note on this subject. 



Mr. E. M. Nelson exhibited a small and extremely pretty 

 portable microscope, which had been made by Mr. Baker. It 

 was remarkably firm in use, having a large spreading tripod 

 foot 6in. to 7in. wide. It was fitted with a rack-work coarse 

 and a direct acting screw fine adjustment — a chromatic 

 doublet substage condenser, with an iris diaphragm attached, 

 focussing by a sliding tube — and it had both plane and concave 

 mirrors. The body extended to 6^in. by a draw tube, and its 

 weight altogether was 21b. He was sure that this would lie 

 found a very useful travelling microscope. He also read a note 

 " On Correcting the Errors in Camera lucida Drawings." The 

 picture drawn in this way, in order to be accurate, should be 

 drawn on the inside of a spherical shell ; and if drawn on a plane 



