58 



THE POTATO CHOP. 



able to a putrefactive action, commencing with the organs, 

 and not with the products of the plant affected. In an 

 analysis of a diseased and of a sound tuber of the same 

 crop, the following results were obtained: 1 



Although, from the proportions of starch remaining 

 unchanged, the disease was probably not far advanced in 

 the tuber examined, still we see that a great change had 

 already taken place in its structural arrangement, by the 

 disappearance of the proximate nitrogen compounds, which 

 form a principal ingredient in its organs and juices. These 

 compounds containing nitrogen, being of a more complex 

 composition than starch is, enter far more readily into fer- 

 mentation and decomposition when placed under favourable 

 circumstances ; and this tendency to change, if unchecked, 

 communicates itself to all the other parts of the potato- 

 the starch included with which it is placed in contact. 

 As long, however, as the starch remains unchanged the 

 potato is more or less fit for use as an article of food, and 

 but little injured for the purposes of the starch manufacturer. 

 But directly a change commences in the starch granules 

 themselves (see woodcut), its value is greatly deteriorated for 

 both purposes, and unless utilized immediately, 'it speedily 

 becomes reduced to a pulpy and offensive mass. If test- 



1 Prize Essay " On the Nature and Cause of the Potato Disease," by G. 

 Phillips. Roy. Agri. Soc. Jour., vol. vii. p. 300. 



