42 



" If I am correct in my views — and I think the facts I have 

 brought forward are in accordance with Mr. Dobree's — then it 

 follows that in the British Isles and in the mountains of 

 Europe it is essential to the imagines of Lepidoptera that 

 they should rapidly take advantage of transient gleams of 

 sunshine, and this the darkening of their coloration enables 

 them to do. 



" I have myself seen Vanessa urtica fall helpless in its 

 flight when the sun passed behind a cloud in spring ; and in 

 the wet summer of 1879 the rapidly-flying A rgynnis paphia 

 was easily captured with the fingers, having taken refuge in 

 the brambles when disturbed, because it was unable to fly. 

 If this occurs in the south of England, it would be much 

 more likely to occur in the more northern parts of these 

 islands, and in the Alps. 



" In conclusion, I cannot but express my admiration of 

 Mr. Dobree's excellent paper, which is a most valuable 

 addition to the literature of melanism." 



Mr. George Smith, of the Sciopticon Company, then 

 gave an exhibition of photo-micrographic lantern slides, 

 being photographs of the enlarged image of the microscopic 

 object printed from metal plates by the Woodbury process, 

 the negatives having been furnished to the Company by Mr. 

 F. H. Evans. The slides were thrown on a three-feet screen 

 by means of the " Sciopticon " lantern, which was fitted with 

 a dissolving apparatus for the purpose of changing the slides. 

 The objects were illuminated by reflected, transmitted, or 

 polarised light, and were remarkable for the extraordinary 

 depth of focus obtained in the photographic negative. A 

 large number were opaque objects, and among the most in- 

 teresting slides were diatoms in situ on coralline ; Arach- 

 noidiscus ornatus ; groups of the Foraminifera ; Polycistina ; 

 Ceratospyris ateuchus ; sponge spicules, Echinus spines, and 

 examples of the class Asteroidea ; spinnerets and jaws of the 

 garden spider, Epeira diadema ; parasites of the cat, horse, 

 sparrow, humble bee, ox, elephant, etc. ; Cecidomyia pectoralis, 

 Anagrus incaratus, Cynips terminalis ; spiracle and eye of 

 Dysticus marginalis, L. 



