OBSERVATIONS UPON DOUBLING OF FLOWERS. 381 



developed pollen. In the petunia the doubling of the flower is 

 usually accompanied by a remarkable modification of the pistil 

 — in short, a secondary flower is formed within the ovary. Bot- 

 anists have long recognized an exceptional development of the 

 floral axis which has been termed prolifi cation. In this there may 

 be a prolongation of the axis beyond the blossom, and the devel- 

 opment upon it of ordinary foliage. The European larch fur- 

 nishes a good illustration of this. Sometimes an ordinary leafy 

 stem extends upward from the center of the cone for nearly a foot. 

 In rare cases leafy branches have grown out from the i free or 

 blossom end of pears, and buds and long branches have arisen 

 from the center of a rose. In the petunia this prolification, if we 

 may call it such, assumes the form of a small and much-contorted 

 flower. Repeated examinations of normal flowers fail to show 

 any unusual structure to the pistil. It is, therefore, associated 

 with the doubling process in the petunia. Instead of the end of 

 the floral axis, which terminates at the base of the single centrally 

 situated pistil, remaining as such, it develops into another flower, 

 and this within the ovary of the primary blossom. Just why we 

 should have this peculiar form of prolification, or any, in fact, is 

 not for us to decide. The ordinary forces which would construct 

 a normal flower have been thrown into confusion, and retrograde 

 metamorphoses and floral prolification have resulted. In fact, it 

 seems evident that out of the substance ordinarily producing a 

 capsule of petunia-seed has been formed in the same ovary an 

 amalgamation of stamens, petals, and a rudimentary pistil. In 

 short, the tendency to petaline display does not stop with the 

 stamens, but invades the pistil, and transforms it as already de- 

 scribed. 



After doubling has once become established, and the tendency 

 is an hereditary trait, it still remains true that surrounding con- 

 ditions may favor or modify it. It is well known that among 

 wild plants the absence of favoring surroundings will hasten the 

 period of reproduction, and even augment the yield of fruit. 

 With doubled flowering plants it may be that they strive toward 

 the same end, but fall short because of non-reproductive tenden- 

 cies developed in them by long-continued culture for their showy 

 flowers only. 



A eelationship between the flora of eastern Asia and of eastern North Amer- 

 ica was pointed out, as to Japan, by Dr. Asa Gray thirty years ago. It has been 

 illustrated since by discoveries of new species alike in both regions, but they have 

 been for the most part unimportant herbs. Greater force is now given to the 

 fact by the discovery, by Dr. Augustine Henry, that the Chinese and American 

 tulip-trees are identical. The discovery is significant in that it gives evidence that 

 the climates of eastern America and of China have continued to be alike since the 

 Tertiary period. 



