162 PRINCIPLES AND CONCLUSIONS. 



and 11 visits, at 2 meters 1 inspection and 9 visits, while the mixture 

 of artificial and natural heads yielded 23 visits. When 2 imitation heads 

 of Helianthus annuus were placed on stems with closed buds, they received 

 2 inspections by Bombus and 13 incidental visits from muscids chiefly, 

 while 33 insects ignored them entirely. The number of inspections was 

 increased when the 2 imitations were placed among 15 normal heads, 



9 insects coming to inspect and 2 to alight, among them being Apis and 

 Bombus. With 3 normal and 2 artificial heads, 27 insects ignored the latter 

 as they flew past, and 5 inspected them. In order to test the attraction 

 exerted by the materials used in ordinary artificial flowers, a head bought 

 in a store was added to the two previously used. The result was that the 



10 inspections observed either took place before this one head or began 

 with it, indicating that the starch or dye employed in it served as the 

 attraction. Twelve heads of Leucanthemum vulgare bought in the trade 

 were attached to a plant bearing 1 open head and 25 to 30 buds, but re- 

 ceived a single incidental visit and no inspections. The next experiment 

 was organized by placing 5 imitations among 30 open heads of the same 

 plant and putting a group of 7 artificial heads at a distance of a meter. 

 No visits were made to the latter, in contrast to 3 to those on the plant 

 and 53 to the normal ones, thus indicating that the natural flowers furnished 

 the attraction for the others. 



The most comprehensive series of experiments was made with Centaurea 

 cyanus, in which both bought and specially constructed artificial flowers 

 were employed. Six clusters of 3 heads each of the former were attached 

 to plants with the buds still closed, which grew near groups of Melandrium 

 and Anchusa actively visited by bees. Apis and Bombus inspected the 

 false heads 30 times and extended the ligule before them 5 times. When 

 artificial heads made for the purpose were employed, Apis made 1 inspection 

 and Bombus 5 only. However, these were made a year later and under 

 different conditions of weather and competition. The author admitted 

 that the bees frequenting the adjacent flowers gave evident attention 

 to the imitation heads, but stated that they perceived them only from a 

 short distance, attraction from a distance seeming not to exist or to be 

 very feeble so far as the artificial heads were concerned. When 18 of the 

 commercial flowers were put at 2 dm. from a group of normal ones, they 

 obtained 15 inspections and 2 extensions of the ligule in comparison with 

 54 visits to the latter, while the special imitations when placed in and 

 about a nearly equal number of natural heads received but 9 inspections. 

 In a series of 5 comparative studies with both kinds of artificial heads 

 the figures were essentially similar, though the inspections were more marked 

 with the commercial heads. Altogether, the cornflowers attracted insects 

 somewhat more than the other artificial flowers. 



Conclusions as to artificial flowers. — Because of their value in sum- 

 ming up the results of his three investigations with artificial flowers and giving 

 his final views on the subject, Plateau's conclusions are here stated in detail : 



"With respect to the solution of the question whether insects are or are not seriously 

 attracted by artificial flowers, these new and extensive experimental studies are 

 almost useless, since they serve only to confirm in full the results of my earlier re- 



