1x1 
Nature; and they have become, through natural selection, beautiful, 
or rather conspicuous, in contrast with the greenness of the leaves 
that they might be easily observed and visited by insects, so that their 
fertilization might be favoured. I have come to this conclusion from 
finding it an invariable rule shat when a flower is fertilized by the 
wind it never has a gaily-coloured corolla. Again, several plants 
habitually produce two kinds of flowers; one kind open and coloured 
so as to attract insects; the other closed and not coloured, destitute 
of nectar, and never visited by insects. We may safely conclude that 
if insects had never existed on the face of the earth, the vegetation 
would not have been decked with beautiful flowers, but would have 
produced only such poor flowers as are now borne by our firs, oaks, 
nut and ash trees, by the grasses, by spinach, docks and nettles.” 
Moreover, we obtain from these facts the best evidence that insects 
possess the faculty of perceiving and distinguishing colours. For as 
regards the vision, and indeed the other senses of insects, we have 
yet much to learn. We do not yet thoroughly understand how they 
see, smell, or hear; nor are entomologists entirely agreed as to the 
function or the structure of the antenna. This interesting subject 
offers a most promising field for study, and I would particularly call 
the attention of entomologists to a remarkable memoir by Hensen 
on the auditory organ in the decapod Crustacea, which first appeared 
in the ‘ Zeits. f. wiss. Zool.,’ vol. xiii. p. 319, and_of which an abstract 
has been given in the ‘ Quarterly Journal of Microscopical Science,’ 
vol. v. p. 31. Hensen has shown that (as had been stated by 
M. Faivre) the otolithes in the open auditory sacs of shrimps are 
foreign particles of sand, introduced into the organ by the animal 
itself. He proved this very ingeniously by placing a shrimp in 
filtered water without any sand, but with crystals of uric acid. Three 
hours after the animal had moulted he found that the sacs contained 
many of these crystals. 
M. Hensen has also shown that each hair in the auditory sac is 
susceptible of being thrown into vibration by a particular note, which 
is probably determined by the length and thickness of the hair. It 
may be experimentally shown that certain sounds throw particular 
hairs into rapid vibration, while those around them remain perfectly 
still. 
_ M. Baudelot has published, in the ‘Annales des Sciences Natu- 
relles,’ a short memoir on the influence of the nervous system on the 
