PKOCEEDINGS OF THE SOCIETY. 391 



the case. As regarded the influence of spherical aberration, the actual 

 diameter of the ring would not at first be rapidly disturbed, and the 

 imperfection of the instrument employed would have to be considerable 

 before its influence would become sensible, an^ he knew that Mr. Nelson 

 had used a variety of objectives and telescopes, many of which were of 

 the best quality, so he did not think that the source of error would be 

 found in this direction. 



Mr. Nelson's paper " On an Improved Vertical Illuminator " was 

 read by Dr. Hebb. 



The President said it was rather early in the evening to complete 

 the reading of the papers, ])ut there were so many interesting objects in 

 connection with " Pond Life " arranged for their inspection, that he was 

 sure they would be glad to have ample time for the examination of the 

 beautiful objects which had been brought for their inspection. He was 

 sure they were much obliged to the exhibitors. 



Votes of thanks were unanimously passed to Professor Porter and 

 Mr. Nelson for their papers, and to those Fellows of the Society and 

 ]\Iembers of the Quekett ^Microscopical Club who had brought objects 

 for exhibition to the Meeting. 



Notice was given that at the close of the ordinary business of the 

 next Meeting on June 19, the Meeting would be made special for the 

 consideration of a proposed alteration in Bye-law No. 65a. It was 

 also announced that at the next ]Meeting a lecture would be given by 

 Mr. F. Enock, with lantern illustrations. 



The following Instruments, Objects, etc., were exhibited : — 



The Society : — A Traviss Expanding Stop for dark-ground illumina- 

 tion. Membranipora monostachys var. fossaria, a brackish water 

 Bryozoon from Great Yarmouth, from Mr. H. E. Harrell. Melkerta 

 ringens and Volvox gJohator from Mr. John Hood. 

 Mr. F. TV. Watson Baker : — PJumatella reiwis. 

 „ T. N. Cox : — Spirogyra. 

 „ R. E. Crossland : — Vorticells. 

 „ T. A. Delcomyn : — Desmids. 

 „ J. Dick : — Marine organisms. 

 „ A. Downs : — Hydra viridis and Volvox gJohator. 

 „ F. Enock : — 12 eggs of a Hemipteron (plant bug). Each Q^g 



containing from 1 to 6 Ovivorous Parasites. 

 „ T. D. Ersser : — Water mite. 

 „ W. Gardner : — GristateUa mucedo. 

 „ A. E. Hilton : — Cyclosis in leaf of water thyme {Elodea 



canadensis). 

 „ E. Hinton : — Lophopus crystalUmis. 

 „ J. T. Holder -.—Steplianoceros Eichliorni. 

 „ T. G. Kingsford : — Conjugation of Spii'ogyra. 



