14 MESSRS. NEWELL ARBER AND J. PARKIN ON 
however, be argued that the closed condition would be as effective for wind 
pollination as the open carpel. А definite, receptive part of the closed 
sporophyll could catch the pollen wafted by wind as easily as the ovule of an 
open one. True, but on the supposition of a multiovulate carpel, the closed 
state would not be so effective for anemophily, since the chances are that 
insufficient pollen would reach the stigmatic surface to fertilise all the ovules. 
By entomophily, on the other hand, large masses of pollen, sufficient for the 
fertilisation of all the ovules, would be deposited on the carpel, as the result 
of a single visit. This view is borne out by the fact that most anemophilous 
Angiosperms have uniovulate carpels. 
There is this further consideration that, by the closing in of the carpel, 
more efficient protection is afforded to the developing ovules and seeds, and 
at the same time the chance of their being pollinated is increased by the 
localisation of the collection mechanism. The insect has only to leave the 
pollen on one part of the carpel, whereas to fertilise each ovule of a 
multiovulate open carpel it must be deposited on or near each ovule. 
Though agreeing so far with Robertson, we part company with him when 
he suggests that honey, and not pollen, first attracted insects to flowers. 
The converse seems to us the more probable, and besides offers a better 
explanation of how entomophily arose. Otherwise how are we to account for 
the evolution of floral nectaries ? The seerction of honey previous to insect 
visitation does not appear likely. Afterwards, of course, the plant would 
gain by substituting this cheaper food-material in the place of pollen. It 
could then exercise considerable economy in the production of the latter, 
quite apart from the fact that entomophily in itself is less wasteful in this 
respect than anemophily. It is unnecessary here to trace further the 
evolution of the Angiospermous flower under insect influence. This study 
belongs to a special branch of botany, the main results of which are general 
knowledge. 
While we regard the entomophilous condition as a primitive feature among 
Angiosperms *, there are numerous instances in which a return to the older, 
anemophilous habit has, more recently, taken place. These are frequently 
associated with the more extreme cases of reduction from the amphisporangiate 
to the monosporangiate condition, accompanied by suppression, often complete, 
of the perianth. Against the view that such anemophilous plants are 
primitive may be urged the fact that the inflorescence is almost invariably of 
a dense, complicated type, while the style, and especially the stigma, are 
obviously highly evolved structures, fashioned on the same plan as pertains 
in entomophilous flowers. 
* Henslow (1898*) p. 266; Wallace (1889) pp. 323-4. 
