I7 8 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 oedema of the tomato is a swelling of certain 



6z. (Edema 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 : 



" i. 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). 



