92 QUAHTERLYJOURNAL. 



crop has been a total loss. The failure of such an article, which 

 has formed the chief dependence of the poorer classes for food, is 

 calculated to excite intense alarm, and the investigation of the 

 cause of the disease, and some remedy for it, becomes a subject of 

 the highest importance. It is not my intention to offer any thing 

 as to its nature or cause, for notwithstanding all that has been 

 written upon it, I regard it, as yet, utterly in the dark. The sur- 

 mises in regard to the disease, afford a striking example of the too 

 great tendency in our farmers to frame theories, without sufficient 

 ground. Instead of collecting facts, and making extensive obser- 

 vations, and then comparing them, the discovery of every new fact 

 and sometimes z. false, fact^ has given rise to an explanation which 

 has seemed entirely satisfactory to the mind of the individual who 

 has noticed it, but unfortunately to no one else. I do not say this 

 is true in all cases, for there are some which may approach to the 

 truth. But I must be pardoned if I bestow upon others all the 

 ridicule with the pen, which I have upon reading them. I shall, 

 in what follows, endeavor to state the individual conjectures about 

 the origin of this disease, and some reason for not giving full be- 

 lief to them. 



1. Chemical defect — either in the soil or in the tuber, produces 

 a tendency to decay. 



2. Unfavorable weather — occurring about the time the tuber was 

 forming. 



3. An insect — injuring the root — directly, or by its ravages in 

 the stem. 



4. Honey-dew — a substance about which nothing is known. 



5. Improper care — in keeping the root through the winter. 



6. Manuring in the hill. 



7. Manuring the land. 



8. Atmospheric causes. 



9. Fungtis. 



10. Degeneracy in varieties — from long cultivation. 



11. Degeneracy in varieties — from propagating by seed. 



This is a full list, so far as I have seen or heard of suppositions 

 upon the subject. I will now proceed to state them more fully. 



1. Chemical defect. It is very natural for a chemist to suppose 

 this to be the case at first view ; but when it is remembered that 

 there is hardly any portion of world where the potatoe is culti- 



