TIIE POLLINATION OF THE PRIMROSE 317 



own shores. Knuth at Kiel has failed to observe insect visitors, and 

 Cobelli in the Tyrol can, besides four beetles and Thrips, only name 

 one butterfly (Qonepteryx rhamni) as a visitor capable of cross- 

 fertilizing the plant. He specially notes tbe fact that bees avoid it." 

 Knuth however, subsequently modified his statement ; in his Sand* 

 book of Flower Pollination, p. 69, he records (1909) Bombus lior- 

 torum and Anthophora pilipes as visitors. 



In 1902 the Kev. E. Bell gave some account of his own very 

 extensive field-observations (The Primrose and Darwinism), and 

 stated (p. 30-1) that he had only noticed four insect visitors "after 

 seeing and examining thousands and thousands, we might say 

 millions, of the flowers." He concluded that " the Primrose gives 

 unimpeachable evidence that self-fertilization of heterostyled plants 

 is the natural and legitimate fertilization as being fully productive." 

 Bell's book contains much that is of a polemical nature, but his 

 observations are those of an able and accurate naturalist and an 

 original and painstaking observer. 



In 1903, the problem attracted the attention of Professor Weiss, 

 who in April of that year devoted eight days at Church Stretton 

 (Shropshire) to an endeavour to secure further information. He 

 records (New Phyt. ii. 99-105) five types of visitor in this area, 

 these, in order of frequency, being Andrena Gwynana, Bomby litis 

 major, Anthophora pilipes (misrecorded as A. furcata Panz. ; ^see 

 Nature Notes, xv. 101 (1901)), Bombus terrestris, and Apis mellijica. 

 He writes: — "There is no doubt in my mind that Primroses are 

 efficiently cross-pollinated in the district under observation by Bom- 

 bi/lius, Anthophora, and Andrena with the addition of occasional, 

 though by no means isolated visits of Bombus.'''' " The fact that 

 many observers have been unable to detect such insect visitors I 

 attributed to their observations having been made either in cool or 

 dull weather, or in exposed and windy situations. For even on sunny 

 days I could not observe the usual insect visitors in wind-swept 

 localities, while, at the same time, in sheltered positions some larger 

 humble-bees might occasionally be met with." He concludes : — 

 " From observations I have made on the Primrose I feel convinced 

 that it is both regularly visited and cross-pollinated by insects under 

 favourable climatic conditions, but that, like most flowers adapted 

 to the visits of insects, it is provided with efficient means of self- 

 pollination, and these are important to a plant flowering at so early a 

 period of the year when the visits of insects may be precarious." 



"Weiss's paper, which represents a distinct advance and helps to 

 reconcile conflicting views, was followed by a critical review by Bell 

 (Nature Notes, xv. 63-8 ; 1904), who held that the length of the 

 corolla-tube of the Primrose (12-16 mm.) " excludes the vast majority 

 of insects, and even the majority of what are called the long-tongued 

 insects, as the humble-bees, from reaching the nectar. The humble- 

 bees consequently are not accustomed to visit it." Only one humble- 

 bee (Bombus hortoruni) could reach the nectar with any facility, 

 while it is inaccessible to the hive-bee (Apis mellijica). He dis- 

 misses Scott Elliot's meagre statement (Fl. Dumfriessh. 114 ; 1896)— 

 " Bombu.s hortorum, regular and sufficient visitor" — as unsatis- 



