248 



Palate of Periwinkle 

 Section of Horse-chestnut 

 Elytron of Alpine Beetle 

 Hydra vulgaris ... 

 Eggs — Cottvs quadricomis 



„ Gvbius niger 

 Avqjhiipleura pellucida, with l-25th oil 



immersion object glass, N.A. 1*38, and dry 



achromatic condenser... 

 Starch-cells from Euphorbia splendens 

 Growing point with latex cell, Euphorbia,-) 



splendens ... ... ... ... ; 



Stigma of Vinca major ... 



British Butterfly with protruding tongue 



Injection — Duodenum of Cat ... 



„ Intestine of Rat 



Bock section Mekqjhyre, Heinbach ... 

 Porphyry, Elfdalen, Sweden, showing fluidal } 



structures ... ... ... ... i 



Section of a Meteorite from West Liberty, Iowa 

 Eggs, Planorbis corneus (living) 

 Striped voluntary muscle, Human Tongue ... 

 Parametrium aurelia and Stylonychia ) 



treated with tannin ... ... ... J 



Stomach of Cat ... 



Ovary of Cat 



Trichina spiralis, encysted in Human muscle 



Hornblendic Granite from Cleopatra's Needle 



Mr. M. D. Xorthey. 



Mr. J. M. Offord. 



Mr. F. A. Parsons. 

 >> >> 



Mr. Powell. 



Mr. J. W. Reed. 



>> 



Mr. F. Reeve. 

 Mr. W. Smart. 



Mr. G. Smith. 



>» 5» 



)> >> 



Mr. A. W. Stokes. 

 Mr. J. G. Tasker. 



Mr. H. J. Waddington. 

 Mr. W. D. Wickes. 



Mr. J. Willson. 



April 13th, 1883. — Conversational Meeting. 



The fifth of the demonstrations was given by Mr W. T. Suffolk, F.R.M.S., 

 on " Microscopic Vision," in one of the College Class Rooms. 



In his opening remarks Mr Suffolk observed that he wished to bring 

 before the members some delicate optical experiments in order to illustrate 

 and explain the discoveries made by Professor Abbe some ten years ago, 

 and which up to the present time few people knew anything about, and 

 fewer still believed in. 



With regard to microscopic vision, there was a diagram to be found in 

 nearly every book on the microscope, in which diagram the object-glass 

 was represented as forming an image at a certain distance behind it, that 

 image being again magnified by the eye-piece. The diagram was correct 

 so far as it went, but when an object possessing minute detail was 

 examined, no matter whether the structure was lined, dotted, or granular, 

 so long as it was minute enough, another factor came into the calculation, 

 which was known as diffraction . 



