396 MEANS OF CROSS-FERTILISATION. CHAP. X 



and seedlings were raised from each kind in four 

 separate beds. In all the beds mongrels of various 

 kinds were numerous, except amongst the ten seedlings 

 from the blood-red onion, which included only two. 

 Altogether forty-six seedlings were raised, of which 

 thirty-one had been plainly crossed. 



A similar result is known to follow with the varieties 

 of many other plants, if allowed to flower near together : 

 I refer here only to species which are capable of 

 fertilising themselves, for if this be not the case, they 

 would of course be liable to be crossed by any other 

 variety growing near. Horticulturists do not commonly 

 distinguish between the effects of variability and inter- 

 crossing ; but I have collected evidence on the natural 

 crossing of varieties of the tulip, hyacinth, anemone, 

 ranunculus, strawberry, Leptosiphon androsaceus, orange, 

 rhododendron and rhubarb, all of which plants I believe 

 to be self-fertile.* Much other indirect evidence could 

 be given with respect to the extent to which varieties 

 of the same species spontaneously intercross. 



Gardeners who raise seed for sale are compelled by 

 dearly bought experience to take extraordinary pre- 

 cautions against intercrossing. Thus Messrs. Sharp 



* With respect to tulips and rhinum, the varieties of which are 

 some other flowers, see Godron, known to cross freely, because 

 1 De 1'Espece,' torn. i. p. 252. For these plants are not always self- 

 anemones, ' Gard. Chron.' 1859, fertile. I know nothing about 

 p. 98. For strawberries, see Her- the self-fertility of Trollius (Le- 

 bert in ' Transact, of Hort. Soc. coq, ' De la Fe'condation,' 1862, 

 vol. iv. p. 17. The same observer p. 93), Mahonia, and Crinum, in 

 elsewhere speaks of the sponta- which genera the species intercross 

 neous crossing of rhododendrons. largely. "With respect to Mahonia, 

 Gallesio makes the same state- it is now scarcely possible to pro- 

 ment with respect to oranges. I cure in this country pure speci- 

 have myself known extensive mens of M, aquifolium or repens; 

 crossing to occur with the common and the various species of Crinum 

 rhubarb. For Leptosiphon, Verlot sent by Herbert (' Amaryllidacse,' 

 'DesVarie'tes,'1865,p.20. I have p. 32) to Calcutta, crossed there 

 not included in my list the Car- so freely ttat pure seed could not 

 nation, Nemophila, or Antir- be saved. 



