232 Modern Entomology. (April, 
Mr. Darwin himself, however, was, I believe, the first 
to show that, if a flower be fertilised by pollen from a 
different plant, the seedlings so produced are much stronger 
than if the plant be fertilised by its own pollen. I have had 
the advantage of seeing several of these experiments, and 
the difference is certainly most striking. For instance, six 
crossed and six self-fertilised seeds of [poma@a purpurea were 
grown in pairs on opposite sides of the same pots; the 
former reached the height of 7 feet, while the others were 
on an average only 5 feet 4inches. The first also flowered 
more profusely. It is, moreover, remarkable that in many 
cases plants are themselves more fertile if supplied with 
pollen from a different flower, a different variety, or even, as 
it would appear in some instances (in the passion-flower for 
instance) from a different species. Nay, in some cases, 
pollen has no effect whatever, unless transferred to a 
different flower. Fritz Miiller has recorded some species 
in which pollen, if placed on the stigma of the same flower, 
has not only no more effect than so much inorganic dust, 
but, which is perhaps even more extraordinary, in others 
he states that the pollen placed on the stigma of its 
own flower acted on it like a poison. This he noticed 
in several species: the flower faded and fell off; the pollen 
grains themselves and the stigma in contact with them 
shrivelled up, turned brown, and decayed; while other flowers 
on the same branch, which were not so treated, retained 
their freshness.” 
It may be urged that the fertilisation of flowers by means 
of insects is a process liable to be frustrated by a number of 
accidents. Thus a bee or a butterfly may go from one 
flower to another of a totally different order, when the 
pollen it conveys will of course be wasted. Sir J. Lubbock 
enumerates, however, several species of bees which confine 
themselves to particular flowers. Thus Andrena florea 
visits no other flower save that of Bryonia dioica, whilst 
Macropis labiata restricts itself to Lysimachia vulgaris. 
Why certain flowers are fecundated by bees, and others 
chiefly by moths, is an unexplained question. In some cases 
the long proboscis of a sphinx may reach into the tubes of 
flowers where no bee could penetrate. It would almost 
seem that bees are more generally attracted by colour, and 
moths by odour. Every entomologist knows that vinegar, 
porter, or rum—all strong smelling liquids—is a necessary 
ingredient in the mixture used in “ sugaring” for moths. 
From the wonderful development of their antennz, we should 
infer them to possess the sense of smell in singular perfection. 
