THE VARIETIES OF FERTILISATIOJST. 317 



SO carefully ci'ossed iu nature, nor self-fertilisation so carefully 

 prevented, as was the case in his experiments. The probability 

 is that the two processes are much more mixed in nature in 

 the case of most plants. Therefore, by his experiments the 

 more unalloyed influence of crossing brought about a much 

 more enhanced stimulus than ever occurs in the wild state. 

 Moreover, the prepotency of foreign pollen, upon which he 

 lays stress, is a purely relative phenomenon ; for whenever 

 self-fertilisation yields more seeds than intercrossing, as is 

 often the case, it is a just inference that the pollen " of the 

 same flower " is then prepotent, in its turn. Indeed, Mr. 

 Darwin actually found that in some cases intercrossing did 

 no " good " at all, as in the case of the Garden Pea mentioned 

 above, and in Canna Warscewiczi, etc. 



I will now add some observations upon certain points 

 I have numbered in this paragraph. 



(1) That Lobelia raviosa and Digitalis ptirpnrea, and many 

 others given in a "List of Plants Sterile without Insect-aid," * 

 cannot readily fertilise themselves unless the flower be 

 disturbed in some way, is, per se, no proof that self- fertilisa- 

 tion is injurious ; for the flowers of many of such plants are 

 fully self-fertile when artificially assisted. Thus, Mr. Darwin 

 says that although L^lpinus luteus and L. pilosus seed freely 

 when insects are excluded ; yet Mr. Swale, of Christchurch 

 in New Zealand, found Lupins only formed pods of seed 

 when the stamens were artificially released, as they are not 

 there visited at all by bees.f The interpretation of this 

 fact, so well known that the term " hercogamous " J has 

 been invented for it, I take to be an immediate result of 



* Cross and Self Fertilisation, etc., p. 357. 

 t i.e., p. 150, note. 



J If I remember rightly, by Errera ; see Bull, de la Soc. Bot. de Belg., 

 xvii. (1887). The term means a " fenced-off union." 



