380 the president's address. 



tion of the structure of these marvellous organs in a well-known 

 paper in Kolliker's " Zeitschrift " about 1857; and he did more, 

 for he investigated the development of the compound eye at a time 

 when next to nothing was known about the development of special 

 organs in insects. The number of papers which have since ap- 

 peared is very great. As you all know, I am myself fighting the 

 question, and I believe that my views,* which are optically and 

 physiologically tenable, and which are based on anatomical facts, 

 demonstrated by slides, admitted by the best judges to be far 

 more perfect than any others which have been exhibited, and 

 by photographs made by our old friend Mr. Nelson, are in a 

 fair way to be accepted by the leading English biologists. I 

 may also say that I am told that Professor S. Exner of Vienna, has 

 lately demonstrated an optical picture in the entire compound eye, 

 which corresponds to the surface of my retina. If this is so, and 

 I am only waiting for the return of more genial weather and living 

 insects to make the experiment, my views cannot fail to be generally 

 accepted without further delay. 



Amongst those who have attempted to make experiments for 

 the purpose of discovering the functions of the organs in insects I 

 would mention M. Faivre's experiments on the nervous system of 

 dytiscus in 1857, Sir John Lubbock's interesting experiments 

 on the Hymenoptera published in the Journal of the Linnean 

 Society, and the long series of experiments which have been carried 

 on for fifteen or twenty years by Professor Plateau, of Ghent — 

 records of which I still receive from time to time from their 

 learned author. We all feel that such experiments are greatly 

 needed, but at the same time regret that, owing to the complexity 

 of the phenomena observed, we are still very much in the dark with 

 regard to the manner in which the various functions are carried on, 

 and with regard to the correct interpretation of the phenomena 

 observed. The subject is still further rendered obscure by the 

 difficulties which arise from the testimony of different observers 

 being somewhat contradictory. 



The organs in insects to which we must probably ascribe the 

 function of ears are very unlike the auditory organs of vertebrates. 

 Our knowledge of these structures is pre-eminently due to the 

 elaborate researches and splendid papers of Professor Vitus Graber, 



* " Linn. Trans.," Ser. ii., « Zoology," Vol. ii., 1884. 



