FERTILIZATION IN THE VEGETABLE KINGDOM. 229 



by the astonishingly small quantity produced by cleistogene 

 flowers, which lose none of their pollen, in comparison with 

 that produced by the open flowers borne by the same plants ; 

 and yet this small quantity suffices for the fertilization of all 

 their numerous seeds. Mr. Hussall took pains in estimating 

 the number of pollen-grains produced by a flower of the Dan- 

 delion, and found the number to be 243,G00, and in a Peony 

 3,654,000 grains. The editor of the ' Botanical Register ' 

 counted the ovules in the flowers of Wistaria sinensis, and 

 carefully estimated the number of pollen-grains, and he found 

 that for each ovule there were 7,000 grains." — (pp. 376, 377.) 



These are probably fair averages of the numerical ratio 

 of pollen to ovules in flowers which are adapted to be fertil- 

 ized by insect agency. Their meaning in the " economy of 

 nature " is seen by a comparison on the one hand with ane- 

 ?nophilous, i. e. wind-fertilized, flowers, in most of which there 

 is a vastly greater disproportion between the numbers, — com- 

 pensating for inevitable waste, — and on the other hand with 

 cleistogenons flowers, namely, those small and less developed 

 blossoms which some plants produce in addition to the ordi- 

 nary sort, and which fertilize as it were in the bud, necessarily 

 by their own pollen. Here is no waste, and accordingly the 

 anthers are very small, and the pollen-grains are not many times 

 more than the ovules : also such flowers are never brightly 

 colored, never odoriferous, and they never secrete nectar. 



The only advantages of this close-fertilization which we 

 can think of are sureness and strict likeness ; both of which 

 are quite as well secured by budding-reproduction. Now, as 

 cleistogene flowers are borne, we believe, chiefly and perhaps 

 only, by species whose normal blossoms are adapted for insect- 

 fertilization, they must be regarded as a subsidiary arrange- 

 ment, a safeguard against failure of proper insect-visitation. 

 As the volume before us amply shows, this failure is in gen- 

 eral provided for by a more or less wide margin of self-fertil- 

 ization in the very flowers which are adapted for crossing. In 

 Impatiens, Viola, and the like, it is provided for by separate 

 flowers, the special adaptations of which are unmistakable. 



H. Muller appears to have shown " that large and conspic- 



