QUEKETt MICROSCOWCAL CLUB. 343 



aquatic method of pollination still obtains. The- resin canals vary 

 in number and position in different species, and identification is 

 almost possible by tbe examination of a transverse section of the 

 leaf. Pines, being very inflammable, have suffered badly during 

 the hot dry summer by fire, and it is interesting to notice the 

 repopulation of the clearings. The pines do not appear at first, 

 but the deciduous trees — oaks, beeches, etc. — come up. Then 

 the pines shoot up, and after a few years overshadov/ the other 

 trees and re-establish the pine growth. 



A very hearty vote of thanks was accorded to Mr. Addey for his 

 very interesting lecture and for the series of slides projected on the 

 screen in illustration of the subject. 



At the 565th Ordinary Meeting of the Club, held on December 

 13th, 1921, Mr. Eobert Paulson, F.L.S., F.R.M.S., Vice-President, 

 in the chair, the minutes of the meeting held on November 8th, 

 1921, were read and confirmed. 



Messrs. Arthur L. Butler, Fredk. William Payne, B.A., James 

 Mein, W. James David Roberts, Alfred E. Harris and Dr. Alfonso 

 Gondolf Hornyold were balloted for and duly elected members 

 of the Club. Eleven nominations were read for the first time. 



The Secretary announced that it had been decided to hold no 

 meeting on December 27th, and that at the next meeting, on 

 January 10th, Dr. Tierney would read his paper on " Mosquito 

 Investigation." 



Mr. D. Bryce exhibited a specimen of a mite found at Melbourne 

 parasitic on Termites. The Hon. Secretary announced that he 

 had received some copies of Mr. Darlaston's catalogue of micro- 

 scopical sHdes. The Chairman then called upon the Hon. 

 Secretary to read Mr. E. M. Nelson's paper, " On the Focus 

 Aperture Ratio." This important subject, said Mr. Nelson, has 

 been dealt with on three previous occasions — by Prof. Abbe, by 

 the R.M.S., and by Mr. Nelson himself. The problem is to suggest 

 the most suitable ratio between the power of objectives and their 

 N. A. If the ratio is too low there is " empty magnification," if too 

 high aberrations are sure to be evident. He found experimentally 

 that the resolving power of the human eye is 1/250 in. at 10 in., 

 and then determined the N.A. necessary to resolve this amount 

 with a given objective, using a x 10 eyepiece for a long tube or 

 JouRN. Q. M. C, Series II.— No. 88. 24 



