1882.] and their Recognition. 523 
attributed to a perfeCfly arbitrary ad of Divine will. Now 
a great approximation has been made to the truth of viewing 
both the odours and the colours of flowers as means for 
attracting such butterflies, moths, and birds as may aid in 
the process of fertilisation. It is further held, on the prin- 
ciple of natural economy, that colour and odour are mutually 
substitutes for each other. In faCt this is what is observed 
in a multitude, perhaps in the majority, of cases. Many of 
the most brilliantly coloured and conspicuous flowers are 
scentless, whilst on the same principle many of the most 
richly perfumed blossoms are white or pale yellow. 
But to this rule there are a number of exceptions which 
require serious consideration. Not a few flowers of a decided 
colouration are well known for their sweet smell. As fami- 
liar instances I may take the hyacinths, the sweet peas, the 
stocks and wallflowers, the pinks and carnations, the red 
rose, the oleander, the auricula, the cyclamen, and the 
violet. The last-mentioned flower is, however, very incon- 
spicuous, and it is highly probable that it is indebted to its 
scent alone for the visits of bees. The original types of the 
auricula and of the wallflower were presumably the light 
yellow varieties we so often meet with. But though there 
are white oleanders, their original colour is in all probability 
red, and the same may be said of the pink and carnation. 
We have also to deal with the fadt that so many white 
flowers are totally scentless, — for instance, the large wild 
convolvulus, and the pear- and plum-blossom. This pecu- 
liarity may seem less perplexing if we consider that perfume 
must be more especially serviceable for attracting night- 
flying insert visitors, such as moths. Now the white con- 
volvulus, like all its tribe, is a day-opening flower, and is 
always found tightly folded up at night. The white scent- 
less fruit-blossoms open at a season of the year when few 
night-flying inseCts have made their appearance ; conse- 
quently their fertilisation must depend on the visits of bees 
and butterflies. The questions then arise — Are any flowers 
which close at nightfall odoriferous ? and, on the other 
hand, are any species which bloom only in the night scent- 
less ? These points can only be studied to advantage in 
tropical countries, where many flowers open and close at 
fixed hours of the. day, as was shown in the “ floral dial ” 
drawn up by Linnaeus. 
Another interesting circumstance is the number of flowers 
which emit odours more or less offensive to our sense of 
smell. Among these rank many well-known garden favourites 
— dahlias, peonies, the tropaeolums (commonly called 
2 M 2 
