230 CANNA WABSCEWICZI. CHAP. VI 



selected and measured. The eight tallest crossed plants averaged 

 30-92, and the eight tallest self-fertilised 30 '7 inches in height, 

 or as 100 to 99 ; so that they were practically equal. But we 

 should bear in mind that the trial was not quite fair, as the 

 self-fertilised plants had a great advantage over the crossed 

 in being much less crowded in their own row, owing to the 

 large number of seeds which had perished under ground after 

 sprouting. Nor were the lots in the two rows subjected to any 

 mutual competition. 



XXIX. CANNACE.ZE. CANNA WARSCEWICZI. 

 In most or all the species belonging to this genus, the pollen 

 is shed before the flower expands, and adheres in a mass to the 

 foliaceous pistil close beneath the stigmatic surface. As the 

 edge of this mass generally touches the edge of the stigma, and 

 as it was ascertained by trials purposely made that a very few 

 pollen -grains suffice for fertilisation, the present species and 

 probably all the others of the genus are highly self-fertile. 

 Exceptions occasionally occur in which, from the stamen being 

 slightly shorter than usual, the pollen is deposited a little beneath 

 the stigmatic surface, and such flowers drop off unimpreg- 

 nated unless they are artificially fertilised. Sometimes, though 

 rarely, the stamen is a little longer than usual, and then the 

 whole stigmatic surface gets thickly covered with pollen. As 

 some pollen is generally deposited in contact with the edge of 

 the stigma, certain authors have concluded that the flowers are 

 invariably self-fertilised. This is an extraordinary conclusion, 

 for it implies that a great amount of pollen is produced for no 

 purpose. On this view, also, the large size of the stigmatic 

 surface is an unintelligible feature in the structure of the flower, 

 as well as the relative position of all the parts, which is such 

 that when insects visit the flowers to suck the copious nectar, 

 they cannot fail to carry pollen from one flower to another. * 



* Delpino has described (' Bot. are fertilised in the bud, and that 



Zeitung,' 1867, p. 277, and ' Scien- self-fertilisation is inevitable. I 



tific Opinion,' 1870, p. 135) the presume that they were misled by 



structure of the flowers in this the pollen being deposited at a 



genus, but he was mistaken in very early period on the pistil : see 



thinking that self-fertilisation is ' Journal of Linn. Soc. Bot.' vol. 



impossible, at least in the case of x. p. 55, and ' Variability dcs 



the present species. Dr. Dickie and Especes,' 1868, p. 158. 

 Prof. Faivre state that the flowers 



