6 
BULLETIN" 601, U. S. DEPARTMENT OF AGRICULTURE. 
the thermometers was about 40° F. It has been determined that 
this point is about as low as the ice in the bunkers will hold the load. 
TREATMENT OF EXPERIMENTAL LOTS. 
As has been stated, the precooled car contained an experimental 
lot consisting of an equal number of hampers of lettuce carefully cut 
and commercially cut from the same field at the same time. An 
exactly similar lot was shipped at the same time in a refrigerator 
car that was not precooled. The two cars went to the same market, 
in most cases to New York City, where a representative of the Depart- 
ment of Agriculture inspected them upon their arrival and again 
three days later. 
Comparable lots, both precooled and nonprecooled, were held at 
Palmetto in an iced refrigerator car and kept under approximate 
B 
«f 
y. 
HP Iff mW^^" *^l 
it mL^*2* 
1 -* ^*N^J 
■ a ■'■ i ' m9 ^' v ^ i * m A^f3SSIHK^i^ s ^ 
Fig. 4. — Two heads of lettuce, showing the difference in methods of cutting: A, Commercially cut 
B, carefully cut. 
transit temperature conditions. It was possible to keep the tempera- 
tures in this holding car under close control, so that, these lots give 
a good index of the effect of temperature on the development of 
decay. Six days after cutting — the average length of time required 
for the cars to reach the principal northern markets — the lettuce was 
removed from the holding car and inspected. It was then held at 
ordinary temperatures for three days and again inspected. Accurate 
records were kept as to the general condition of the lettuce and the 
amount of decay at each inspection. 
RESULTS OF EXPERIMENTS IN 1913-14. 
SHIPPING LOTS. 
During the season of 1913-14 nine full comparable experimental 
lots were shipped to northern markets and 16 lots were held in 
Palmetto. The following tables and diagrams give a summary of 
