EXPERIMENT STATIONS. 191 
days after fertilization has been effected, the petals drop off and the 
calyx tube is parted over the now slowly swelling ovary and drops off, 
When pollination has not been effected, the blossom continues fresh 
for several days,although the stigma may have become covered with 
dust and withered and become non-receptive, and it finally drops 
off, the peduncle remaining fora day or so longer. The peduncle 
lengthens to nearly its full length from the time the blossom bursts 
from the bud until fertilization is complete and, when legitimately 
fertilized, enlarges in diameter. When fertilization has been illegit- 
imately effected the peduncle does not enlarge in diameter as much, 
and the slightly enlarged ovary usually falls, together with the pe- 
duncle, within from three to twenty days after fertilization. The 
season of full bloom ranges in different varieties over a period 
of about ten days. The past season, 1894, my earliest blooming 
varieties were in full bloom May 2d and the latest May 10th. 
The actual time in the life of a blossom during which fertilization 
may be effected scarcely exceeds two hours and is not, as many sup 
pose, during the whole life of the expanded flower. 
LEGITIMATE AND ILLEGITIMATE FERTILIZATION. 
From the many artificial crosses that I have made and recorded, I 
long ago became convinced that fertilization might be effected in 
different degrees and that many plants had the power of throwing 
off such ovaries as were fertilized by pollen lacking in sexual af- 
finity and that this wasespecially truein P. Americana. Itshould 
be borne in mind that the production of seed is the chief end of the 
act of fertilization and the vivification of the ovule is the primary 
object of pollination. By systematic crossing and hybridizing, I 
determined that the union of the reproductive elements of two trees 
possessing the proper selective affinity for each other readily pro- 
duced a stronger developement of the ovary; a union of this kind I 
shall call legitimate. 
Itis well known that by crossing distinct species fertilization is 
effected with more or less difficulty; that reciprocal crosses of the 
Same two species vary in the intensity of fertilization. As tothe 
union of the reproductive elements of varieties lacking in sexual af- 
finity for each other or in which the reproductive elements have 
become too greatly differentiated and the development of the ovary 
either fails entirely or is below the normal, I shall use the term il- 
legitimate, and in the same sense as used by Darwinin his “Different 
Forms of Flowers on Plants of the Same Species.” The simplest 
test to determine the sexual affinity of any variety, and one which 
Ihave never known to fail when done under proper conditions, is 
to take séveral sets of flower clusters and pollinate each individual 
stigma with pollen of a different form. The union of such crosses 
as possess the proper degree of affinity will prove fertile, while the 
union of those lacking in affinity will prove sterile. No matter how 
many of the flowers of each cluster are pollinated legitimately or 
illegitimately, the result will be as above. If all of the flowers of a 
cluster are pollinated legitimately, they will all set fruit, barring 
accident, of course. This experiment may be modified by many 
different combinations. 
