6 BULLETIN 27, POETO RICO EXPERIMENT STATION. 
may be planted. The crown or upper part of the root is the most 
satisfactory part for planting, because it is less desirable as food 
and better able to withstand exposure, bruises, or unfavorable 
weather longer after planting than other parts. When it is profit- 
able to market the crop before the proper time to plant a new crop, 
the crowns may be left in the soil for a number of weeks after the 
remainder of the root has been removed. This can be done by re- 
moving from one side of the plant all the soil until the entire edible 
root is exposed, dividing the root at the desirable point, and remov- 
ing the lower section. Care should be exercised to avoid injuring 
any of the feeding roots which are spread laterally in all directions 
from the crown. The hole from which the earth is removed should 
be immediately refilled so that the plant can continue to grow and 
develop strong buds. Each plant has from two to four buds or 
eyes. The lower part of the yam has a much higher water content 
than the crown, and consequently it is more susceptible to injury and 
decay than the upper part. It is also slower in starting into growth 
than the upper part, and should not be used unless seed yams are 
scarce. 
The experiment station found that a goocl percentage of sections 
(taken from the largest roots) sprouted when placed in a cool, shaded 
place, and made a normal growth when transferred to the field. The 
crown and part just below usually send out from two to four sprouts 
promptly, and may be divided longitudinally with good results pro- 
vided the piece of the root is large enough to supply nourishment 
for the young plant. 
To secure heavy yields, seed pieces of good size should be planted. 
One to 2-ounce pieces are often planted in Porto Kico, but pieces 
weighing from 4 to 5 ounces should be used. Tests made at the sta- 
tion with different sized seed pieces of common varieties and with en- 
tire tubers of some of the small-rooted varieties showed that a good 
gain in yield was made by using large rather than small seed pieces. 
TREATMENT OF SEED ROOTS. 
Poor stands of plants are usually caused by sections of the roots 
decaying before the vine growth starts. The following treatments 
were given a number of seed pieces to test their efficacy in preventing 
the entrance of decay through the cut surface of seed pieces : 
The cut surfaces of one lot were covered with air-slaked lime; 
those of another lot were exposed to the sun for one day; two lots 
were treated with Bordeaux mixture, one as soon as the roots were 
cut and the other after drying in the sun for 10 hours. An untreated 
lot was placed in the storage house as soon as it was cut. 
