432 M. A. Kerner on the Protection of Pollen 



attract insects, they are generally not remarkable either for 

 colour or perfume ; their perianth is generally yellowish or 

 greenish and often scaly ; the stamens, instead of being hidden 

 at the bottom of a corolla, are attached to movable catkins, 

 or they push themselves (as in the grasses) above the floral 

 envelope. 



Tn every way a considerable quantity of pollen is lost ; it 

 falls to the earth without reaching the stigma, or it is damaged 

 by moisture. All the plants of this category obviate this in- 

 convenience by producing enormous quantities of pollen (e. g. 

 the positive clouds of yellow powder which frequently surround 

 the Conifers at the moment of flowering). 



But in still more numerous cases the pollen must be con- 

 veyed to the stigma by insects ; and from this flows a multitude 

 of consequences which greatly influence the form and appear- 

 ance of the flowers. Thus the perianth will always be more 

 or less coloured or odoriferous, to attract insects ; the grains 

 of pollen are not dry and free as in the previous cases, but 

 always more or less adherent to each other, being retained by 

 a product of the degenerescence of the mother cell, which M. 

 Kerner regards (wrongly we think) as bassorine. The degree 

 of cohesion is extremely variable, from the solid pollen-masses 

 of the Orchidese and Asclepiadea? to the pollen of a great 

 number of plants which presents little conglomerations easily 

 dispersed. 



In these plants the pollen is produced in quantities infinitely 

 smaller than in the anemophilous plants. Moreover there is 

 a more or less considerable lapse of time between the opening 

 of the anthers and the moment when the fecundating dust is 

 carried away by insects ; and it is absolutely necessary that 

 during this time it should be protected from the deleterious 

 influences of wind and moisture. The most various parts of 

 the flower may be charged with this function ; and it is the 

 examination of the different cases which he has had the oppor- 

 tunity of observing that forms the greater part of M. Kerner's 

 memoir. 



The reproductive organs themselves are often charged with 

 the protection of the pollen. Thus, in the iris the stigmata 

 are developed into broad petaloid plates bent outwards and 

 meeting the lobes of the perigonium ; they thus completely 

 envelope the anthers in a sort of narrow channel, through 

 which insects must of necessity pass when going to collect the 

 nectar, but into which neither wind nor rain can penetrate. 

 In the genus Aspidistra the corolla takes on the form of a 

 widely open cup, at the bottom of which are the extremely 

 short stamens ; the stigma is developed into a broad disk 



