IOWA ACADEMY OF SCIENCES. 
79 
One of the objects of the work undertaken in this con- 
nection was that of throwing some light upon the time 
interval between pollination and fertilization in the plum. 
It is a common belief among nurserymen and horticultur- 
ists that although the pollen is applied to the pistil and 
germinates, fertilization and consequent development of 
the embryo is delayed for some time. This necessitated 
a study of the pistil, ovule and embryo sac in their devel- 
opment. A few observations were also made on the per 
cent of aborted pistils in the different plums, and a study 
was made of these aborted pistils to determine, if possible, 
whether the trouble was structural. Observations were 
further made on the different problems that are connected 
with pollination, fertilization and development, including 
a study of the aborted ovule that is to be found in every 
normal plum ovary. 
For a study of the early development of the flower buds, 
material was gathered during the fall and winter and 
sectioned free hand. As soon as the buds began to swell 
in the spring, the material was gathered and hardened in 
Chromic acid or Platinic chlorid for twenty-four to forty- 
eight hours. It was then washed, infiltrated and imbedded 
in paraffin, and cut in serial sections. The most satis- 
factory stain was the triple stain of Anilin Safranin, 
Gentian Violet, Orange G. Many other combinations 
were tried, but none were more satisfactory. Material 
was gathered daily just before and during the blooming 
season, and thereafter every second or third day until the 
embryos were mature. The Wyant, one of the Americana 
plums, and the Poole’s Pride, one of the Wild Goose type, 
were the forms taken for study. 
According to the observations made at Ames, the first 
indications of the formation of the flowers is to be found 
in the fruit buds in the axils of the leaf a little before the 
middle of July. This agrees well with the observations of 
Professor Goff in Wisconsin (9) who finds them formed 
about this time. These flowers make their appearance 
first as slight swellings on the interior of the bud near the 
