276 DEPOSITION OF POLLEN. 



probosces except at the apex of the cone of anthers, and in consequence the head 

 alone and not the abdomen is, in this case, besprinkled with pollen. In Soldanella 

 (figs. 278 1 and 278^) the apex of each anther is produced into two little processes. 

 Insects come against them as they enter the flower, with the result that pollen is 

 scattered out of the anthers. Several of the wonderful contrivances which were 

 described on p. 271 as occurring in connection with stamens fashioned like sugar- 

 tongs are also present where the conical arrangement of anthers prevails; and we 

 need not, therefore, discuss the latter at greater length. The only case left requir- 

 ing special attention is that of the Violet and Pansy ( Viola, fig. 279 ^). Unlike the 

 foregoing, the flower in this case is zygomorphic and has its mouth directed side- 

 ways, and moreover, the manner in which the anther-cavities, which are full of 

 floury pollen, are moved by insects is peculiar. The cone of anthers is set over 

 the lowest petal, which is prolonged at the back into a spur containing honey. 

 In order to suck the honey an insect must push under the cone and run its 

 proboscis along the channel of the spurred petal. But here it encounters the 

 thickened extremity of the hooked and deflexed style, which it cannot avoid 

 touching and shifting a little. The five stamens forming the cone are closely 

 adherent to the style, so that any displacement of the latter affects them also, and 

 the moment this happens the proboscis of the intruding insect is besprinkled with 

 pollen from the dislocated cone of anthers. 



DEPOSITION OF POLLEN. 



The pollen which has been taken from one flower has to be deposited in another 

 by honey -sucking insects and birds. How, when, and where the deposition occurs 

 is of great importance, as the transference is in reality the first stage in the series 

 of events leading to fertihzation. The stigma is the destination of the pollen, and 

 the right moment for deposition is as soon as the stigma is able to hold fast the 

 pollen which is brought to it. If the pollen is not deposited on the stigma but on 

 some other part of the flower, or if the stigma be dry and shrivelled, and not able 

 to retain the pollen when deposited on it, it is as much wasted as if it had fallen 

 on to the ground or into the water. Hence not only the time and place of deposi- 

 tion, but also the state of the stigma determine exactly the conditions for the success 

 of the transference of the pollen. 



If the pollen is scattered on the back of the insect the stigma must come into 

 contact with its back; if it has adhered to the proboscis, the insect must stroke the 

 stigma of the newly- visited flower with its proboscis; if the under surface of its 

 body is covered with pollen, then the stigma will be placed at the bottom of the 

 entrance to the flower, so that the insect must stroke it wfth its belly. Obviously, 

 then, an insect, whether abstracting or depositing pollen, will follow approximately 

 the same course in the flower, and that position of the anthers most suitable for the 

 shedding of the pollen will, on the whole, be the position most suitable for the 

 stigma to assume in receiving pollen. It might, therefore, have seemed more natural 



