Medical Officers of the Army of India.
51
the walls of the ovaries of the gall flowers will be found to have become
reduced to thin membranes which have ruptured and from which there have
escaped a number of little insects. These insects are of two kinds,—
one a species of Blastophaga; the other* an insect which was at one time
referred to the genus Ichneumon, from its supposed habit of preying on the
Blastophaga; but which is now known not to be an Ichneumon, and not to be
carnivorous, These insects are present in both sexes; the males (Plate X, Figs. 9,
14, and 16) being ochre-coloured, slowly crawling and wingless; and the females
(Plate X, Figs. 11, 12 , and 13) being bright, active creatures, with shining black
bodies, two pairs of unequally sized pellucid wings, and long ovipositors. In
many cases these insects can be seen in the act of escaping from the ovary
where they passed their pupa stage (there is only one hatched in each ovary).
These insects either die in the cavity of the fig for want of an opening to go
out by, or they escape into the open air by a hole which is bored by the male
Blastophagas through the scales which close the mouth of the fig.
I have never caught one of the small maggots above alluded to in the act
of entering a gall flower there to establish itself as a pupa; but I think it highly
probable that these maggots are the larval stage of the so-called Ichneumon.
Count Solms-Laubach believes that the mature Blastophaga passes its ovipositor
down through the stigma and style of the gall flowers and deposits its egg in the
ovarian cavity of the gall, and I therefore presume that he must believe that
the young Blastophaga thus originating goes through all its changes in the same
ovary. He nowhere, as far as I am aware, mentions having seen the maggots
which I have described. Such of the insects thus hatched as leave a fig may
undoubtedly carry out with them some of the pollen which is being shed at the
time of their escape, and if the channel of escape has been cut (as is so often
actually the case) through the scales of the ostiole, the relation of the anthers
to such an opening makes it highly probable that pollen is thus removed by them.
And in any case the coincidence of the maturation of the pollen with the assump-
tion of the imago stage by the insects, is a fact which has undoubtedly either
some physiological or some evolutionary significance. But how pollen thus
removed can be conveyed into the interior of the receptacles in which the perfect
female flowers are confined, or whether it is indeed conveyed there at all, are
parts of the problem which I submit for solution.
So far as I have observed, the receptacles in which the perfect and fertile
female flowers are situated are closed from the earliest stages. The scales of
the mouth of the young receptacles are thick and fleshy, and they so completely
interlock, that it is difficult to conceive of any organism passing from outside,
between them, into the cavity of the receptacle, carrying any extraneous matter,
such as pollen, with it. The perfect female flowers possess perfect embryos from
a very early stage, and I have not been able to see pollen on any of their stigmas.
Yet, as I have already said, the majority of them produce perfect seeds.
* This so-called Ichneumon has, I believe, been named by Prof. G. Mayr, to whose paper I have not
at present access.