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Personally I observed them, besides in the above named plants, in 
Mimulus Tillingii, M. hybridus, Incarvillea Delavayi, Martynia 
fragrans, M. formosa, and M. proboscidea. 
In all these plants the stigma consists of two broad lips which, 
in normal state diverging under a considerable angle, on being 
touched approach each other and close. 
In nature this closing of the lobes of the stigma is caused by some 
insect penetrating the flower in order to get to the nectar. The 
structure. of the flower does not allow the insect to reach the 
honey without touching the lips. So if an insect withdraws from 
the flower, the before widely opened stigma is seen to have closed 
during the visit. 
Furthermore it has been observed that if the stigma is only 
touched by the insect, the lobes will soon open again, but that 
they remain shut when the insect has at the same time rubbed 
off on them some of the pollen it carried along. 
In my experiments on fertilisation with Torenia Fournieri: my 
attention was roused by the different behaviour of the lobes of the 
stigma, according as the pollen was taken either from the two 
shorter or from the two longer of the four didynamous stamens. 
If the pollen was taken from the shorter stamens, the stigma 
reopened after a few minutes, but the lips remained closed when the 
pollen had been taken from one of the longer ones. 
It should now be remarked that the anthers of the two longer 
stamens of this Torenia burst during the flowering and bring their 
pollen to the surface; those of the short ones, however, don’t open. 
As a rule we find after the fertilisation the anthers of the short 
stamens still closed in the fallen corolla. 
For the rest they are completely developed and their remaining 
closed is the only difference to be observed in these anthers. 
A soft pressure of the anthers with a piece of glass will suffice to 
collect on it all the contents of the two cells, and now it also 
appears that the pollen freed in this way does not differ from that 
of the longer stamens. As a proof of its complete maturity may be 
added that just as well as that of the longer stamens it begins to 
germinate in a drop of distilled water, after 2 hours, if the precau- 
tion has been taken to put at the same time a stigma of Torenia 
in the drop of water. 
I have moreover found that fecundation is as well effected by it 
as by the other pollen. 
So the only difference, between the freely expelled pollen from 
the longer stamens and that enclosed in the shorter ones is found, 
