12 BULLETIN OF THE BUSSEY INSTITUTION. 
to think infection does not take place through the blossoms, —a 
view which cannot now consistently be taken. The evidence 
shows that the disease is of the nature of a variegation due to a 
weakened constitution (brought about by an unfavorable climate) 
acted upon by enzyms which in nature are carried by the pollen from 
tree to tree. If the ovule is fertilized by the enzym-containing- 
pollen, the enzyms may either affect the germinating capacity of 
the seed or remain dormant for a period, until some unfavorable 
environment of the tree starts them into activity and an ordinary 
outbreak of ‘* yellows” is manifested. Under domestication the 
‘¢ yellows ” are propagated by planting seedlings so affected, or if 
sound seeds are planted the enzyms are transferred to the healthy 
stock by means of budding, and the disease is perpetuated. 
Downing* insisted that the ‘‘ yellows” was in the nature of a 
constitutional taint, but no heed was paid to his warning. It 
was the custom of the nurseryman to gather the stones indiscrim- 
inately for stocks. | | 
The practical conclusion which may be drawn from this experi- 
ence is that, to avoid the ‘‘ yellows” as well as other diseases, 
we must look to the internal qualities of the stock—as has 
been done with many other plants — rather than to external 
remedies, or to the enacting of laws for the suppressing of symp- 
toms or ‘‘ gross appearances”? of the disease. We might profit 
by the advice given long ago by Lindley and quoted by Down- 
ing* ; ‘** All seeds will not equally produce vigorous seedlings ; 
but the healthiness of the new plant will correspond with that 
of the seed from which it sprang. For this reason it is not suf- 
ficient to sow a seed to obtain a given plant; but in all cases 
where any importance is attached to the result the plumpest 
and healthiest [and most thoroughly acclimated] seeds should be 
selected, if the greatest vigor is required in the seedling; and 
feeble or less perfectly formed seeds, when it is desirable to check . 
natural luxuriance.” This advice is now being followed, at least 
in some localities. According to Hon. Charles W. Garfield, of 
Michigan, since the appearance of the scourge of ‘* yellows” in 
that State peach growers are more careful to select stock which 
is sound, and has not been grown where ‘‘ yellows” is known to 
prevail. By this method of selection there is a greater probability 
of obtaining stock which has become acclimated. 
* Fruit and Fruit Trees of America, pp. 464, 465. 
