448 
IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
Over one thousand permanent slides have been prepared which 
contain only longitudinal median sections of as many terminal 
buds of the apple cyme. 
To date, the results are rather indefinite, as all material and 
data have not been' studied. A few of the most important facts 
follow. 
Flower and leaf buds started to differentiate as early as July 
1 and continued to differentiate till September 15, but by far 
the largest percentage started to form between July 20 and 
August 10. 
The fruit bud formation is closely correlated with the growth 
of the trees. This showed up strongly in the Jonathan, for flower 
buds became differentiated on July 1 on a tree that had a diam- 
eter increase of .218 inch while on the tree of the largest 
growth with .517 inch diameter increase the flowers did not 
form till September 8. 
Buds from the same type of spurs were found to show over 
a month difference in time of development and those borne 
terminally on long wood growth were found in some cases to be 
two months behind the flowers on the spurs of the same tree. 
From the material so far studied the order of the time of 
flower bud differentiation or start of formation is as follows: 
Jonathan : 
Clover sod. 
Blue grass sod. 
Clover sod. 
Cover crop. 
Clean tillage. . 
Cover crop. 
Grimes Golden: 
Clover sod. 
Blue grass sod, 
Clover sod. 
Cover crop. 
Clean tillage. 
The clover sod plot at the top of the Jonathan list was far 
ahead of the next four plots and the last cover crop was a 
month behind the clean tillage. 
In the Grimes Golden the time of the flower formation was 
much shorter. The clover sod and blue grass sod were very 
close together while the next two, namely the cover crop and 
clover sod, were almost even. The clean tillage was about a 
week behind. 
Department of Botany, 
State College. 
