SHEAR: DISTRIBUTION OF PERISHABLE PLANT PRODUCTS 417 
soil and climatic conditions under which they are grown, methods of 
cultivation and fertilization, nature of the variety, condition as to 
maturity at time of harvesting, methods and care in harvesting, 
grading, packing, and handling previous to shipment, and methods of 
loading, stowing, and bracing in the cars. Any or all these factors 
may be and frequently are involved in the final decay due to parasitic 
or saprophytic fungi occurring in the field or in transit. Hence it 
is of the utmost importance to obtain as complete knowledge as 
possible of the various organisms which attack the particular product, 
their life histories, the time, mode, and conditions of infection and 
development and also their relations to methods of handling and their 
temperature, moisture, and host relations. These problems are 
primarily pathological. 
Growers and shippers long ago discovered that storing fruits and 
vegetables at low temperature prolongs their keeping. This observa- 
tion finally led to the development of commercial cold storage and 
refrigeration methods and practices. These methods and _ practices 
have developed thus far largely along empirical lines. It happens 
that growth in most of the organisms which destroy perishable plant 
products is inhibited at from 33° to 36° F. Therefore, if fruit or 
vegetables, though infected with fungi, are placed under such tempera- 
ture conditions before development of these organisms is too far 
advanced, growth of the fungi will be temporarily suspended. In 
some cases, therefore, refrigeration may simply delay the destruction 
of the product and shift or render uncertain the responsibility for its 
loss which may occur before it reaches the consumer. 
It will appear evident, therefore, that in order to devise methods 
of preventing or avoiding such losses, all the factors involved in any 
particular case must be accurately determined as well as their relations 
and relative importance. Because it is known that certain fungi 
destroy certain fruits and vegetables and that these fungi occur in 
the orchard or on the farm, it has been inferred by some that the 
presence of such organisms on decayed products at destination is 
sufficient evidence that the responsibility for the loss rests with the 
grower. This may be true in the case of some particular product 
affected with some particular disease when shipped without refrigera- 
tion. In the case of refrigerated products, however, our experience 
and that of others has shown that in order to determine the real cause 
or causes and the responsibility for loss in any specific case, the whole 
history of picking, packing, handling and treatment of the product 
must be known, or at least its history from the field to destination. 
This has been very strikingly brought out in the investigations of 
