180 Report or THE BoTANIST OF THE 
Three tubes of this medium carefully neutralized with sodium 
hydroxide, and three tubes unneutralized were inoculated with the 
spongy tissue and kept 24 days in air at a temperature of about 
80° Fahr. Six other tubes of the same medium, three neutralized 
and three unneutralized, were inoculated and kept for the same 
length of time at a temperature of about 80° Fahr. in an atmos- 
phere devoid of oxygen. No growth appeared in any of the 
twelve tubes. 
From the result of this study we conclude that the form of 
apple fruit-spot described above is not caused by fungi or bacteria, 
but what the real cause may be we are not prepared to state. 
Wortmann” observed that starch is present, often in considera- 
ble quantity, in the brown, spongy tissue, while the surrounding 
healthy tissue is almost, if not wholly, destitute of starch. We 
find that the spongy spots lying just beneath the epidermis gen- 
erally contain considerable starch, but the deeper-lying spots 
(which, as has been stated, are formed after the fruit is gathered) 
rarely contain more than traces. This difference in starch con- 
tent is brought out very strikingly when a section of apple show- 
ing both kinds of spots is smeared with a solution of iodine and 
potassium iodide. The sub-epidermal spots become black, showing 
the presence of starch, while the interior spots are not altered in 
color. 
When an apple is bruised without breaking the epidermis the 
_ tissue becomes brown and spongy and resembles somewhat the 
brown, spongy spots under discussion. We have found this 
bruised tissue loaded with starch, while the surrounding unin- 
jured tissue contained no starch. Green apples contain starch 
which is changed into sugar as the fruit ripens. It, therefore, 
seems probable that the bruises which responded to the test for 
starch were made before the fruit was ripe. Upon the death of 
the cells their activities ceased and the transformation of starch 
into sugar was arrested. This theory accounts for the absence of 
starch from late formed spots. | 
23 Loc. cit., p. 663. 
