February jth, 1922.] Proceedings. xv. 



from the simplest form in the mosquito to the most highly 

 developed in the house-fly and that group of flies known as 

 "Bee-Flies " (Syrphidce). The structure of the organs is the 

 same in fundamental design, though differing in detail, and 

 consists primarily of a number of small processes or papillae, 

 almost protoplasmic in appearance, which are directly connected 

 with highly sensory cells. A typical sense-organ may be described 

 as follows : — A semi-circular cavity sunk below a " bottle-neck" 

 closely guarded at the entrance against the ingress of foreign 

 particles, by stiff bristles. On the floor of this cavity are 

 situate the delicate papillae above mentioned; up to the base 

 of each papilla runs a sensoiy cell and the whole organ is 

 embraced by a branch of the large antennary nerve. 



The theories most commonly put forward in regard to the 

 function of these sense pits are that they are olfactory or 

 auditory, or are used in balancing. As regards the two 

 latter views many w^orkers have experimented — with a view to 

 determining the function of the antenna as a whole— by cutting 

 off, varnishing or mutilating the antenna in some way and then 

 observing the behaviour of the fly. So far no very striking 

 results have eventuated from these experiments. 



It is now generally accepted by most entomologists that these 

 sense-pits are olfactory and may serve for the dual perception — 

 in the female of both food and the breeding place — ^in the male 

 of food and the female. 



The slides illustrating the lecture were drawings and photo- 

 micrographs of sections of the antennae of various flies, the 

 magnification being six hundred diameters in some cases and 

 nine hundred and eighty in others. 



Ordinary Meeting, February 7th, 1922. 

 Mr. William Thomson, F.R.S.E., F.I.C. {Vice-Presideyit], in 



the Chair. 



Dr. R. G. Fargher and Dr. J. K. Wood, F.I.C, were 

 nominated auditors of the Society's accounts for the session 

 1921 — 1922. 



A vote of thanks was passed to the donors of the books upon 

 the table. 



Dr. J. K. Wood, F.I.C, read a paper, by himself and Mr. G. 

 E. Collins, M.Sc.Tech., entitled : — 



"The Structure of Stannic Acids." 



Some years ago experiments were commenced by one of the 

 authors with the object of comparing the basic and acidic 



