B. T. LOWNE ON THE STRUCTURE OF THE CORNEA OF THE BEE. 47 



In section this layer is seen to be marked by several hundred 

 crenated lines, caused by the lamina? of which it is composed ; the 

 crenations follow the contour of the facets, the middle layers being 

 almost or entirely without crenations. 



These lines, as well as the indications of the division of the 

 cornea into hexagonal prisms, are best marked in the external 

 portion of the layer. Numerous minute nuclei appear between 

 the laminae. 



When viewed by the aid of polarised light and a selenite, 

 these modifications of structure all become beautifully apparent. 

 Both layers of the cornea polarise, and the colour of the transmitted 

 beam varies from red to green, according to the thickness of the 

 section simultaneously in both. 



As I have already stated in my work on the fly, the mesoderm 

 varies very considerably in its structure. I therefore see no reason 

 to doubt the correctness of the views I have already published with 

 regard to the nature of the cornea in insects, whilst the choroid or 

 pigment layer, as I have stated in the same work, appears to cor- 

 respond to the end ode rm, or innermost layer of the integument. 



If these homologies be correct, the eyes are undoubtedly integu- 

 mental organs, with the nerve structures situated between the two 

 inner layers, the principal seat of the terminal loops of the nerves 

 of ordinary sensation. 



Excursions for 1870. 



The attention of Members is specially directed to the notice, on 

 the cover of this Journal, of the arrangements which have been 

 made by the Excursion Committee for the coming season. It will 

 be observed that during the summer fifteen meetings will take 

 place, seven of which are arranged to fall within the next three 

 months. The first trip will be to Wandsworth Common, which 

 will inaugurate the excursions, on April 2nd, and it is earnestly 

 hoped that a large number of the Members will be found at Clapham 

 Junction on the day named, at three o'clock. The other fixings 

 are for Barnes, Wimbledon, Carshalton, Chiselhurst, Elstree, and 

 Hampton Court. The Excursionists' Annual Dinner, now become 

 an institution of the Club, is down for the 23rd of June, further 

 arrangements for which will be duly announced. 



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