No. 144.] 211 



The Fourth^ and last reason is not so clear to my mind as the 

 others^ but I am inclined to the belief that it may be done so as 

 to prevent the rot, and the reasons for my belief I will give you. 



Suppose that the cause of the rot is a small minute parasite 

 insect that lives and propagates itself in the tubers; that decay 

 follows as a matter of course, when a certain amount of heat 

 develops the disease; that the seed, when planted, retains the 

 germ of the disease, and passes it over to the new vegetable, 

 whenever it is matured sufficient to receive the germ of the para- 

 site. That this has been the cause of the potato rot is plausible, 

 because it is the genuine law by which all parasites perpetuate 

 themselves, and no good reason can be given why this vegetable 

 should be an exception. 



After the sprouts are drawn, consign the potato deep within 

 the compost heap, or the flames, and the work is done. On the 

 other hand, if my theory is not correct, the tubers can be re- 

 planted, and thus be made quite prolific in bringing up another 

 young family. 



You will allow me, if you please, to remark in conclusion, that 

 I hold to the belief that the diseases which afflict the animal as 

 well as the vegetable creation, are nothing more than the opera- 

 tion o^ one general and universal law; that a disease has never 

 yet afflicted man, but that some simple remedy is placed within 

 his reach — so simple, indeed, that it is altogether beneath modern 

 philosopliy to search after it. The same rule exists in the animal 

 and vegetable kingdoms. The only difficulty in the way is, that 

 most men do not search at the foundation of the evil, but cut off 

 the top to effect a cure of the root. 



Mr. Bergen, of Gowanus, desired to knoW' how the tubers 

 which are left in the earth just as they grew, are to be protected 

 from freezing? 



Prof. Mapes — By leaving them untouched, covered by their 

 haulm, which operates as a mulch, they are not protected from 

 freezing, but I'roin too easy thawing ; like my cabbage plants in 

 my cold beds, covered only by boards, where they freeze solid, 



