Queries and Answers* 407 



cimens I could collect. These I have since examined with a powerful mi- 

 croscope, after keeping them for several days in a very humid atmosphere, in 

 hopes of their swelling out from reabsorbing moisture, In this I was only 

 successful where some small depressions in the surface of the stone had pro- 

 tected this tiny vegetable from the unavoidable pressure of the package; but 

 to my regret, it did not, with its shape, resume its splendour under any cir- 

 cumstances in which I could place it. The fronds of the two Jungermannm 

 expanded beautifully ; and as the inter-reticulations were singularly convex 

 and pellucid, I thought they might have acted as lenses to condense the 

 light ; but as some of the stones, which were most splendent, had no veget- 

 able substance on them but the green film already spoken of, this could not 

 be the case. That portion of the film which expanded and resumed its 

 shape, had very much the habit of a Conferva with cylindrical jointed stems 

 and branches, and of it the an- 

 nexed sketch {fig. 106.) is a correct 

 though highly magnified represent- 

 ation. It approaches so nearly to 

 Conferva velutina (Byssus velutina 

 Linn.), that I should at once have 

 referred it to that species, could I 

 find any allusion any where to its ex- 

 cessive brilliancy. I shall feel highly 

 obliged to any of your correspond- 

 ents, who may have observed this 

 striking property, to inform me whe- 

 ther it proceeds from this Conferva, 

 or, if not, from what other minute 



plant, as I am not aware of its being ''^Cl CTT 106 



named by any botanist. Indeed, the metallic lustre, so common on the 

 feathers of birds and on insects, occurs so rarely in vegetables, that I know 

 but of a single well-defined example of it, viz. the capsules and under sides 

 of the fronds of the rare Targionia hypophjlla. Yet I scarcely doubt but 

 the phenomenon I have described has a vegetable origin. It is, I conceive, 

 the effect of light concentrated by the convex form of the inter- reticulations 

 of the pellucid fronds or jointed stems of some very minute plant, and 

 thence transmitted to the eye through the transparent cuticle ; as a glass 

 globe or cylinder, filled with any coloured fluid, will reflect its peculiar co- 

 lour when placed in the shady corner of a room. If the lucid appearance 

 proceeded from minute particles of dew condensed on the surface, it would 

 be either entirely colourless, or tinged with the various hues of the prism, 

 according to the direction in which it was viewed, like the flat gauzy mass 

 of web of the weaving spider, similarly circumstanced. It is, however, always 

 of a vivid golden green, which is the general colour of the juices in mosses, 

 and is only in excess when viewed in one particular angle. Where it oc- 

 curs, the brilliancy seems to be uniformly diffused, as on a plane j though it 

 by no means follows that it is so, as the same effect would be produced by 

 a number of minute, detached, lucid points thickly studded on a dark back- 

 ground. The different appearance of the lenses of the gold-eyed fly, 

 ^emerobius P^rla, when viewed by the naked eye and through a microscope, 

 will illustrate this. Its splendour is, doubtless, enhanced by the surrounding 

 twilight gloom ; but its existence in so obscure a situation adds great weight 

 to my opinion, that it is caused by rays of light concentrated by, and reflected 

 from, the innumerable and inconceivably minute lenses of the leaf, many 

 thousands of which, as the cryptogamic botanist knows, are often collected 

 within an area no larger than the transverse section of a grain of wheat. 

 The idea that it is reflected from the silicious particles of the gritstone 

 could not possibly be entertained by any one who has witnessed its most 

 singular and brilliant character. 



