18G FERTILIZATION OF SPKING FLOWERS ON THE YORKSHIRE COAST. 



hundreds." It is well to remember that the flies are easily scared 

 away, and the bee that goes about its business without caring 

 ibr anybody drives somewhat in this way the lower insects from its 

 collecting grounds. To this extent the classes of insects are mutually 

 exclusive. 



Primula vnhjaris. — The fertilization of this plant is yet un- 

 explained. None of the insects seen on it through many hours of 

 watching are sufBcient for its fertilization. Gibson''' has hazarded 

 that in St. Kilda flies fertilize it, but such is far from proved. 

 Archer Briggsf observed the visitors to it in S. Devon, and records 

 that it is never visited by the larger humble-bees, and only rarely 

 by the smaller kinds. Anthophora acervorum (HI.) and Andrena 

 gwynana (Hm.) are recorded as visiting, and also Gonepteryx rliamni 

 (L.) and Bombylius medius (Dm.). Darwin observed Thrips in the 

 flowers abounding, and while remarking the self-fertilization which 

 tliese insects may bring about, suggests that the flower is cross- 

 fertilized by nocturnal Lepidoptera,| as is its congener P. villosa\ 

 by diurual. Diametrically opposed to the above is Scott Elliot's 

 observation that Bombus hortorum fertilized the flowers, j] 



The doubt does not end with our 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, Gonepteryx 

 rhamni, as a visitor capable of cross-fertilizing the plant. He 

 specially notes the fact that bees avoid it. 



My night observations have been few and not conducted under 

 the best of conditions, and though without results, I incline to 

 Darwin's solution as the right one. Gonepteryx rhamni, recorded 

 by two observers in widely-separated localities, doubtless assists, but 

 its tongue-length (18 mm.) is insufficient to drain the honey of the 

 larger flowers, reaching, according to Knuth, in N. Germany 

 25 mm. in depth. About Scarborough the average depth of the 

 tube varies from 15 to 20 mm., and therefore the honey is beyond 

 the reach of all bees which are on the wing at its flowering season, 

 except Bombus hortorum. 



Nepeta Glechoma may be found gynodioecious — a condition well 

 knownff — from the earliest days of its flowering. 



!ScdLv spp. — All the species observed may be considered together, 



* "The Phanerogamic Flora of St. Kilda," Trans. Bot. Soc. Edinhurrih, 

 xix. p. 155 (1893). 



t " On the Fertilization of the Primrose," Journ. But. viii. 1870, p. 190; and 

 " On the Insects which Fertilize the Primrose," Trans. Phjmonth Institution, 

 iv. p. 188, 1871-2. 



+ Forms of Flowers, pp. 36-37 ; London, 1884. 



§ H. Miiller, " Fertihzation of Flowers by Insects," Nature, xi. (1874)> 

 p. 110. 



II Flora of Dumfriesshire, p. 114, Dumfries, 1896. 



11 "Die Bliiteneinrichtung von Primula acaulis," Bot. Centralblatt, 55, 

 p. 225 (1893). 



** " Osservazioni sulla fioritura e fecondazione della Primula acaulis,'' 

 Verhandl. d. Zool.-bot. Gesell. in Wien, 42, p. 73 (1892). 

 ft Cf. Willis, loc.cit. 



