20 NATIVE BRITISH ORCHIDACE^ 



and longer in the case of waxy pollinia. It takes from 3 to 6 weeks for the pollen- 

 tubes to reach the ovules. ^ 



In 1764 Linnjeus asked whether the influence of the pollen may not be com- 

 municated internally to the ovary of the same flower. According to Sprengel he 

 mistook the pouch of the rosteUum for the stigma. Sprengel himself at first thought 

 that the stigma was a honey-secreting organ. In 1755 Kolreuter had said that the 

 fecundating matter is imparted to the inner surface of the anther-cells. In 1791 Batsch 

 stated that in Orchis, etc., the only way pollen can act on the ovarium is by retrograda- 

 tion of the impregnating power through the caudicle (stalk) of the polHnium to the 

 gland (pouch of the rostellum). In 1 802 Richard thought that fecundation operated 

 without change of place of stamina. In 1824 Prof. Link expressed the opinion that 

 the rosteUum of Richard is without doubt the true stigma. In 1829 Lindley suggested 

 that fertilisation occurred by absorption of fecundating matter from the poUen-masses 

 through their gland into the stigmatic channel.^ 



AU the above thought that orchids were self-fertilising. Lindley, however, in his 

 preface to Bauer's Illustrations of Orchidaceous Plants (1838), in which Bauer figured 

 supposed perforations tlirough wliich the fertilising power of the pollen passed out 

 from the pouch of the rosteUum to the stigma, finaUy rejected this interpretation, 

 and, foUowing Robert Brown, adopted the theory that impregnation occurred tlirough 

 contact of the pollinia with the stigma. Even then the part played by insects does not 

 appear to have been suspected, though Sprengel in 17933 had pubhshed observations 

 of the visits of insects to Orchis latifolia, 0. morio. Platan tbera bifolia, Gjmnadenia 

 conopsea, Listera ovata, Epipactis palustris, and E. latifolia, and figured the removal 

 of poUinia by them. 



It is curious that in Sprengel's days there were two schools of opinion as to the 

 nature and use of honey. Some thought it kept the ovary moist and supple, and 

 preserved the seeds, and that bees were therefore robbers. On the other hand 

 Krunitz said'* that nectar was hurtful if not removed by bees, so that these were 

 beneficent scavengers. 



Orchids are never anemophUous (wind-fertUised), the poUen not being dusty, but 

 consolidated into poUinia in the Monandrae, or immersed in viscid fluid in the 

 Cj^ripediums. They are entirely entomophUous, i.e. poUinated by insects. Some 

 method of attaching the poUinia to insects is therefore essential. PI. B, fig. i, from 

 Darwin's immortal work The various contrivances by jvhich orchids are fertilised by insects, 

 shows the floral mechanism for this purpose of Orchis mascula. The genus Orchis is 

 here dealt with first, although it is the summit of evolutionary progress, because it 



' Camus, Icon. p. 74 (1928). 



^ R. Brown, Trans. Linn. Soc. xvi, 687 (1831). 



3 Sprengel, Das entdtckte Geheimniss ider Natur, p. 403 (1793). '' CEconom. Encjcl. 



