AMPELIDEAE 251 



(op. cit., II, pp. 16 et seq.) twenty-seven different insect visitors {vide infra). These 

 appeared on specially warm days, and a j, belonging to one of the four species 

 of Halictus, was loaded with large balls of pollen derived entirely from grape-flowers. 

 Kirchner (' tjber einige irrtiimlich fiir windbliitig gehaltene Pflanzen,' Jahreshefte Ver. 

 Natk., Stuttgart, xlix, 1893, pp. 98 et seq.) points out that the possibility of transport 

 of pollen-grains by the wind does not prove that anemophily takes place to any 

 considerable extent, for with the wind blowing steadily in one direction, a pollen- 

 grain took 200 hours to reach a stigma tolerably near. And he asserts that this is 

 in direct opposition to all our experimental knowledge of undoubtedly wind-pollinated 

 plants, while the whole structure of the vine-flower as regards stigma and pollen 

 is equally contradictory of anemophily. At the time when the stigma is receptive, 

 it is covered with short papillae, and secretes an abundant supply of glistening 

 stigmatic fluid, which is well adapted to hold any pollen-grains that reach it, but 

 not at all fitted for catching grains, its surface being much too small for such a 

 purpose. Besides, not a single undoubtedly wind-pollinated flower is known with 

 a stigma secreting a sticky fluid. Kirchner goes on to say that the pollen is but 

 slightly coherent, the individual grains possessing a smooth extine, not beset with 

 oil-droplets. It is produced in remarkably small quantity for a supposed anemo- 

 philous plant, and is by no means readily blown away from the dehisced anthers. 

 But were the vine-flower wind-pollinated, the opposite might be expected to a marked 

 extent, since the filaments are rigid, and the anthers firmly and immovably attached 

 to them. The inconspicuousness of the small flowers is counterbalanced by their 

 extreme fragrance, which would undoubtedly suffice to attract numerous insects, 

 if the booty offered were of proportionate amount. But the quantity of pollen is 

 small, and, according to all available accounts, nectar never appears to be secreted — 

 at least in Central Europe — a fact that may well restrain the clever bees from 

 visiting the flowers at a time when so many other copious sources of nectar are 

 available. This deficiency, however, the last piece of evidence supporting the theory 

 of anemophily, is not absolute, for when an observer of the rank of Delpino asserts 

 that nectar is abundantly secreted by the five glands at the base of the ovary, we 

 are obliged to conclude that in warmer regions than ours the vine behaves dif- 

 ferently, and that its flowers do actually produce nectar. According to Rathay, 

 the glands in question are the odour-producing organs. Kirchner is confirmed by 

 Delpino's account in a view long entertained by him, i. e. that in our climate the 

 vine has lost the power of producing nectar which it formerly possessed. It is 

 really a native of warmer regions, but has been cultivated for the sake of its fruit 

 to the utmost possible northern limit. 



The fertilization of the hermaphrodite flowers obviously results from automatic 

 self-pollination, for it is specially favoured by warm still weather. Besides this 

 autogamy, there is no doubt that geitonogamy frequently takes place (Kerner, ' Nat. 

 Hist. PI.,' Eng. Ed. i, II, p. 326), the stigmas receiving pollen from neighbouring 

 flowers. The position and direction of the stigmas do not alter, but the filaments 

 elongate, and curve sufficiently to enable the transfer of pollen to adjacent flowers. 

 Cross-pollination is chiefly effected by insects, as already stated, but it is quite 

 possible that the wind sometimes carries the loose pollen from one flower to others 

 which are not far distant. 



