HISTORICAL. 131 



pollen flowers are visited almost solely by the females. Many fragrant 

 honey-flowers are visited by the males of certain bees with especial fond- 

 ness, but little or not at all by the females of the same species. In cases 

 where the females of a certain species have restricted themselves to a par- 

 ticular flower form or even species for the sake of rapid and certain profit, 

 the males are not affected by such restriction but visit also other flowers. 

 Among those species of bees that visit many flower forms, the females go 

 to the most profitable flowers, the males to the easiest or most fragrant. 

 His demonstration of the presence of the greatest individual differences 

 in color preference also revealed one of the factors involved in constancy 

 (1883:275). 



Bulman's studies.— In a series of papers (1890, 1892, 1897, 1899) 

 Bulman dealt especially with exceptions to the supposed rule of constancy. 



"It is pretty generally believed that the bee is very constant in its visits to flowers, 

 and that when it begins with any particular species it keeps to that until it has obtained 

 its load. But while it is true that bees do show a considerable amount of constancy 

 and often visit a large number of flowers of the same species in succession, they are 

 far from possessing that amount of constancy required by the theory. But it is a 

 well-established fact that bees pass readily from variety to variety of the same species 

 in our gardens. They do not even confine themselves in a single journey to varieties 

 of the same species. In numerous cases I have seen bees visit two, three, or even four 

 species in the course of a minute or two. Hive bees are much more constant than wild 

 bees, yet they pass freely from variety to variety, and not by any means rarely from 

 species to species. As to the latter, take any wild bee, and if you can follow its move- 

 ments for twenty visits or more, the chances are something like ten to one that it will 

 be seen to change its species of flower." 



Among the numerous cases of inconstancy cited, the most striking were 

 those of a bee that made 10 changes in 27 visits to four different species 

 of geranium and of a group of bees that passed from Lavandula to Geranium, 

 Leycesteria, Epilobium, Antirrhinum, and Oenothera. 



Ord's conclusions. — Ord (1897) observed the following routes for two 

 honey-bees: (1) Cytisus 2 visits, Primula 1, Tremandra 1, Eupatorium, rose 



2, white 2; (2) Caltha 7, Ficaria 2, Caltha 3, Ficaria 2, Caltha 3. Bombus 

 made the following journeys: (1) red Tropaeolum 1, yellow 2, red 1, Viola 

 1, red Tropaeolum 2, yellow Calceolaria 1, red 2; (2) Geum rivale 2, inter- 

 medium 1, rivale 1, intermedium 2, urbanum 2, rivale 6, rivale 6, intermedium 



3, urbanum 1. The majority of the apids observed seemed constant to a 

 single species, though this was not true of all the individuals followed for a 

 long time. Few bees were able to resist the temptations offered by a garden. 

 The hive-bee appeared to be fully as inconstant as the wild humble-bees. 

 The most remarkable examples of constancy were observed for Salix, Tilia, 

 Calluna, Mercurialis, and Ajuga. The transfers seemed especially frequent 

 when a number of related plants grew together. 



Plateau and Perez. — The general results of Plateau's studies of con- 

 stancy (1901) have already been given (p. 157). Anthidium and Apis were 

 found to be very constant, the latter affording but 14 examples of incon- 

 stancy during three summers, while Bombus often flew from one species to 

 another and even to a third. P6rez (1903:24) objected to Plateau's re- 



