FLORIDA STATE HORTICULTURAL SOCIETY 
201 
many of our higher plants, germinate 
only under certain conditions of tempera¬ 
ture and moisture. They do not readily 
germinate where the air is perfectly dry 
or when the 'temperature is very low. 
Another object, therefore, of precooling is 
to reduce the temperature down to a 
point where germination of fungus spores 
will not take place. 
There is also considerable misunder¬ 
standing in regard to ordinary refriger¬ 
ation, but few people realizing the length 
of time that it requires for the ice to- fully 
cool the contents of a refrigerator car. 
Temperature records that we have taken 
in fully loaded refrigerator cars enroute 
front Cadifornia and other Pacific Coast 
points, as well as from Georgia, tO' north¬ 
ern and eastern markets, conclusively 
show that it takes the ice from three to 
seven days to reduce the temperature in a 
refrigerator car to a point where the ice 
will finally hold it. During the first part 
of the journey much of the fruit is un¬ 
affected by the refrigeration, and the 
ripening processes and the development 
of decay continue 'under rather high tem¬ 
peratures. The fungus spores germinate 
while the fruit is still warm during the 
first part of the trip and the growth of 
the fungus, though finally somewhat re- 
I tarded, continues somewhat during the 
whole trip. A number of temperature- 
recording trips were made with oranges 
from California to New York under va¬ 
rious methods of refrigeration and pre¬ 
cooling. Under full icing it required us¬ 
ually about seven days to reduce the tem- 
t perature below an average of 45 degrees, 
and I see no reason why Florida oranges 
under full ice should cool much faster. 
During the first three or four days out, 
the decay develops at about the same rate 
as it would under ventilation, and the 
full effect of the icing is not obtained, es¬ 
pecially as regards most of the fruit in 
the car, until the last day or so in transit. 
In the case of Florida shipments under 
full icing, therefore, the fruit is not all 
thoroughly chilled in the majority of cars 
even by the time it reaches the market. 
You should all bear in mind that even 
though precooling has had considerable 
commercial application, particularly on 
the Pacific Coast, it is still more or less in 
the experimental stage and there are still 
ntany problems to be worked out in con¬ 
nection with the application of precooling 
the different varieties of fruits and to dif¬ 
ferent sections. Illustrative of this is the 
problem of rapid cooling. In order to 
accomplish the cooling in the shortest 
time possible, especially in car precool¬ 
ing, some of the fruit, at least, is neces¬ 
sarily subjected to temperatures consider¬ 
ably below freezing. Some varieties of 
fruit can stand very low temperatures 
without injury, while with others it is 
necessary to run the temperatures rather 
high even at the beginning of the precool¬ 
ing process in order to avoid injury by 
freezing or rapid reduction of tempera¬ 
ture. The minimum temperatures that 
the various varieties of fruits and vege- 
tables will stand without injury have not 
yet been fully determined. 
There are two methods of doing pre¬ 
cooling; that is, in the cars after they are 
loaded or in warehouse cooling- rooms 
o 
before the fruit is loaded into the cars 
