358 The Ohio Journal of Science [Vol. XVI, No. 8, 



Besides showing the order in which the tissues are emptied 

 of starch, it also shows how the process is delayed with the 

 age of the stem. Beyond the eighth year no change has taken 

 place by May 12th. Starch has nearly disappeared from all 

 tissues above ground, except the heart wood. 



Thus far, the storage of starch in living branch wood tissues 

 has been considered. For the sake of comparison, sections from 

 the trunk of a tree, with apparently non-living heart wood at 

 the center, were now made. During the last week in January 

 a tree showing 54 annual rings was cut at a height of one foot 

 from the ground, and a series of starch tests made from outer 

 bark to pith along both radii of the diameter. Very little 

 starch was found in the bark. The sapwood just beneath the 

 bark contained a considerable quantity distributed in the wood 

 parenchyma and medullary rays, but mostly in the rays. The 

 amount diminished inward from the bark gradually to the 12th 

 year, then suddenly, from which point no starch was regularly 

 found in the wood parenchyma, except at certain intervals to 

 be described later. From the 23rd year, the wood had the dark 

 brown heart wood color; here starch still occurred in the ray 

 cells, but intermingled with empty cells. At certain intervals, 

 23rd, 37th and 51st annual rings, occurred places where the 

 storage tissues, both rays and wood parenchyma, were densely 

 filled with starch, particularly in the summer wood portion of 

 the ring. Such starch accumulations in the heart wood may 

 possibly be explained on the assumption of "excess storage"; 

 i. e., years when conditions were favorable for the production 

 and storage of starch, followed by a fruitless, or partly fruitless, 

 season. Inasmuch as fruit production is probably one of the 

 principal sources of starch consumption in the tree, one can 

 readily see that a condition of abundant supply would exist 

 with little provision for an outlet, and hence account for the 

 accumulation of starch in the heart wood. The fact that more 

 or less starch is stored in the annual rings throughout the 

 heartwood, and is not used from year to year, but simply 

 remains in the heart wood intact during the life of the tree, 

 suggests a reason for the decay of the trunk and the inner parts 

 of the larger Hmbs of the apple tree. It is well known that 

 starch is one of the best foods for the nutrition of fungi, and 

 when once the spores get access to the stored starch in the 

 heartwood, it is only a short time until the spread of the fungus 



