18 BULLETIN 191, U. S. DEPARTMENT OF AGRICULTURE. 
class of bulbs, based upon this artificial heating, known as "Dutch 
prepared," has been on the market for some years. These are noth- 
ing more than bulbs whose development has been forced by artificial 
heat while in storage. 
Very fundamental changes take place in bulbs while they lie 
" dormant " on the shelves. Should one cut a large tulip bulb open 
through the growing point upon digging, as soon as the leaves have 
died down, he would probably be disappointed in not being able to 
find readily the flower bud; but by September 15, unless low tem- 
peratures have been maintained, the flower will have developed to 
half the length of the bulb, and by the first of November the flower 
may be actually protruding through the tip of the bulb. All this 
growth has taken place in storage and is of tremendous importance 
to the consumer, the florist, and the producer of bulbs, for future 
behavior is largely influenced by these changes which take place 
in the bulb house. The higher the temperature during storage the 
more rapid is the development of the flower spike; consequently, 
the shorter the time necessary for it to come into blossom. A long 
period in storage produces similar results, so that a region which 
is able to dig its bulbs early will have bulbs that can be forced earlier 
than where they mature later and are consequently dug late. This 
fact is well brought out in comparative forcing tests of stocks grown 
in the Netherlands, in Bellingham. Wash., and in Eureka, Calif. 
Bulbs from the last-named locality are the earliest and the Holland- 
grown bulbs the latest to flower. The time was when our early 
forcing stocks were grown almost entirely in southern France the 
year previous to their importation. Xow earliness is brought about 
in Holland-grown (late-dug) bulbs by a process of forcing in stor- 
age. The indications are that, by the selection of the locality, we 
can produce in this country the equal of the " Dutch prepared " or 
French stocks without resorting to artificial processes. 
This all means that to the commercial grower the temperature of 
his bulb house will be such as is natural in the region from July to 
October, coupled with proper moisture control, and that the higher 
the temperature the shorter the time the bulbs can be held out of 
the ground, for after the flower begins to push out of the bulb de- 
terioration takes place very rapidly. 
CLEANING. 
As practiced in the Netherlands cleaning is one of the tedious 
processes of bulb culture, as it is hand labor exclusively. A great 
deal of it, however, can be accelerated by the aid of simple ma- 
chinery. When one has but few bulbs the operation may be done 
by hand, but with lots of several thousand bulbs simple devices are 
time savers. 
