192 MINNESOTA STATE HORTICULTURAL SOCIETY. 
RESULT OF SELF AND CROSS-FERTILIZATION. 
In the diagramatic chart following (plate 2), I have attempted to 
give in the simplest and most condensed manner the results of sever- 
la thousand artificial hand pollinations madeby me during a period 
of five successive years, together with some earlier data and obser- 
vations, all made in a very careful manner and carefully recorded, 
the details of which would be too long and burdensome for this 
paper. Most of my data for pollinations made with pollen of the 
andromoncecious form on the long-styled heterostyled form were 
accidentally lost, and at the time of compilation consisted of but 
three records. I am unwilling at this time to state positively that 
pollination in the above direction would produce legitimate fertil- 
ization; I have, however, on the basis of incomplete data and from 
theoretical conclusions,indicated the probable rule by a dottedline. 
The central column represents the form of pollen used; the lines 
between the different forms indicate the directions in which fertil- 
ization is positive or negative, or,in probably more expresssive 
terms, legitimate or illegitimate. Of the forty-nine possible combi- 
nations, or directions. of pollinations but one form, the hermaphro- 
dite, is fully fertile with its own pollen. Including the hermaphro- 
dite form, cross-fertilization is legitimate in only thirteen directions 
Thus it will be seen that among the seven forms of P. Americana 
pollination is possible in forty-nine directions, thirty-six of them 
giving negative or illegitimate results, and that there are only thir- 
teen directions in which cross-fertilization is possible. 
I know of no group of plants more favorable than the genus 
Prunus for the study of the order of evolution from the hermaphro- 
dite stage to the higher stage of bisexuality. Their organs of re- 
production, asI have shown, present a number of peculiarities of 
morphology and function, unusually interesting and significant 
and at the same time unusually intelligible, nor are these peculiar- 
ities exhibited to the same degree by any other group of plants. A 
study of these numerous adaptations to insure cross-fertilization 
must necessarily end in the conclusion that our species is gradu- 
ally approaching a state of diceciousness, and, fortunately for our 
discussion, there appears to be no missing link in the chain. 
With these numerous adaptations and structures to prevent self- 
fertilization and to insure cross-fertilization in view, we are pre- 
pared to understand why, in the several cases, self and cross-fertil- 
ization is possible, and why impossible; why cross-fertilization is 
possible in acertain direction, while the reciprocal cross may be 
sterile, and, finally, by what means our species is gradually becoming 
dicecious. The wedge of variation, having gained a hold of our 
hermaphrodite form, still in existence and capable of self-fertiliza- 
tion and forced by long continued self and occasional cross-fertili- 
zation, produced the earliest types of our dichogamous group which 
the better insured cross fertilization. In the proterogynous form, the 
pistil, protruding through the still undeveloped petals and stamens 
and receiving the advantage of sunlight, air and warmth, was en- 
couraged to greater development, the stamens being correspond- 
