PER ee er yl ieP eee ek on Neate 
EVERGREENS. 195 
had been retarded. The unsuccessful crosses were made with dif- 
ferentiated pollen on a pistil not sufficiently differentiated. Finally, 
we must conclude that the means by which the bisexual forms have 
been produced, though gradually and necessarily very slow, are 
identical with the forces that produced the different species. In the 
crossing of the different species, we find that by applying the same 
rule for cross-fertilization we can trace the genealogy back to the 
forms wherein the differentiation of the sexual elements had not 
destroyed their affinity. From these experiments we deduce the 
following: 
CONCLUSIONS. 
Self-sterility of Prunus Americana in the heterostyled and bisex- 
ual forms is caused by the great differentiations of the sexual 
elements. 
Pollination by wind and insects cannot be controlled to any extent. 
Mixed planting, therefore, unless it be done with respect to the nat- 
ural affinities of the varieties, may produce the most disastrous 
result for the horticulturist. 
Other species of Prunus observed show these characteristics of P. 
Americana, and it may be possible te bring them together and un- 
der a similar classification. 
Finally we have gained some knowledge in the summary produc- 
tion of hybrids. 
This study is necessarily preliminary to further investigation 
touching horticultural varieties of P. Americana, etc. 
EVERGREEN TREES. 
E. H. S. DARTT, OWATONNA. 
In this world of ours we value things according to their abund- 
ance or scarcity. If gold was as plenty as iron, its value would go 
till the term sixteen to one would become obsolete. So of the beau- 
tiful evergreen tree. In regions where nature has provided for all 
its requirements, it is so very common; but when we approach the 
borders of what used to be known as the great American desert) 
we look upon it as athing of beauty,and we are anxious to study 
out some plan by which we can make it a joy forever. 
Excessive drouth is a great impedimentin the way of the success- 
ful growth of trees. How shall we counteract its influence? I would 
say, first, by preparing a very deep, rich, mellow soil—fora rich soil 
‘will generate and retain moisture much better than a poor soil; 
next,by thorough cultivation, stirring the soil frequently to the 
depth of three inches during periods of drouth; next, by irrigation, 
which must be continuous and thorough, for a little water like a 
little learning is thought to be a dangerous thing, for it quickly 
evaporates and leaves the ground in worse condition than before it 
was applied. In watering a tree, it is thought best to make a slight 
depression about it and give a three foot tree three or four pail- 
fuls, increasing the amount according to the size of the tree. Then, 
replace the soil or mulch and let it rest forten days or two weeks, 
