i9i3' I 9 I 4-] The Common House Fly. in 



rings and the position of the pith, which is near the inner 

 side of the curve, so that almost the whole addition to its 

 diameter was made in the outer side. Why should the cell- 

 formation be so much more active on the outer than on the 

 inner side ? 



[Sections of trees were shown, descriptive of above.] 



At the same meeting a contribution on " Gnats and Mos- 

 quitoes : A Study in Adaptation," with lantern illustrations, 

 was given by Dr Marion I. Newbigin. 



On April 22, 1914, was read the report of Mr W. C. Craw- 

 ford, who went as a delegate to the Meeting of the British 

 Association. Mr Charles Campbell gave a paper on " Spring 

 Migrants," with lantern illustrations ; and Mr D. A. Boyd's 

 subject was " Notes on Phycomycetes and Ustilagineas of the 

 Forth Area" (see p. 180). 



Yl.—THF COMMON HOUSE FLY. 

 By Dr W. G. AITCHISON ROBEBTSON, D.Sc, F.E.C.P. 



(Read October 28, 1914.) 



Though the house fly be small in size, this is no measure of 

 its interest to us not only as microscopists, but as biologists, 

 economists, and lastly as sanitarians. The literature dealing 

 with the fly is most extensive, though, I am sorry to say, 

 chiefly of a condemnatory nature. One has to go far back 

 in history to find an author who gives a tribute of praise to 

 our domestic friend, or enemy as he is so often called. 

 VOL. VII. h 



