78 
IOWA ACADEMY OF SCIENCES. 
of particular instances remain alone to be constructed. In 
recent years many interesting and puzzling questions have 
been raised regarding the life histories and the develop- 
ment of many of our cultivated plants. Several investi- 
gators have undertaken studies of a few of these problems, 
and their results have been most instructive and valuable. 
The contributions which Cannon (5) has made to the study 
of plant hybrids, especially in the maturation of the germ 
cells of the hybrid peas is important as an addition to 
our knowledge of the working of the Mendelian laws. Dr. 
Webber through his investigations of xenia in maize has 
contributed much to our knowledge of the immediate 
effect of pollen on the ovary, and has settled one of the 
most puzzling of cytological and practical problems. 
Attention has been given by various investigators also to 
the subject of fertilization in some of our cultivated plants 
and its bearing on their fertility. Among many might be 
mentioned Profs. Beach and Booth (3) (4) (27) , of the New 
York State Agricultural Experiment Station, who have 
studied the microscopic appearance of the pollen of the 
grape and its relation to fertility, their results being most 
interesting and valuable. 
One of the groups that has received some little attention 
of late years has been that of our cultivated plums. There 
are many interesting problems connected with their polli- 
nation and fruiting, their self sterility and their cross 
pollination. Several phases of these problems have been 
worked up by botanists, and horticulturists, most promi- 
nent being Prof. E. S. Goff, of the University of Wiscon- 
sin, and Prof. F. A. Waugh, of the Vermont Agricultural 
Experiment Station. The former has made a number of 
investigations relative to the abortion of pistils in the 
plum, its frequency and cause. He found that a large per 
cent of the pistils of the Americana group of plums are 
abortive, that is, with pistils incapable of producing fruit. 
Professor Waugh, through a series of years has studied 
quite exhaustively the percentage of abortive pistils, and 
the problems of pollination in plums. These will be dis- 
cussed in another connection. 
