178 TOMATO. 
lent growth consequent upon a dark house, over-watering, 
and unskillful attention to ventilation. Outgrowths or 
swellings closely resembling fungous infections appear 
upon the leaves and stems, and the leaves finally curl 
up (Fig. 61). This trouble has been made the subject of 
a special study by Atkinson,* whose ‘‘summary for 
practical purposes”’ is as follows : 
‘““The cedema of the tomato is a swelling of certain 
61. Gedema of the tomato. 
parts of the plant brought about by an excess of water 
which stretches the cell walls, making them very thin and 
the cells very large. The excess of water may be so 
great that the cell walls break down, and that part of the 
plant dying, exerts an injurious influence in adjacent parts. 
‘““The excess of water in the tissues is favored by the 
following conditions : 
‘‘1. Insufficient light. The long nights of the early 
winter months, numerous cloudy days, and in part, the 
walls and framing of the forcing-house, deprive the plants 
* Bulletin 53, Cornell Exp. Sta. (May, 1893). 
