668 POTATO ROT. 



matter in excess noxious to animal life, though highly important 

 in a due proportion, and in storing up mineral masses, destined 

 in process of time to be of great service to man. 



At a later period more dry land appeared, and the earth be- 

 came covered more with trees and other vegetable growth, by 

 which the carbonic acid became so exhausted as to become fit 

 for the inhabitation of man. 



This exhaustion from various causes, has been going on 

 more or less rapidly, until even man is being affected by the 

 great absorption of carbonic acid gas, as appears by the increase 

 of disease in the respiratory and nervous system of man, one of 

 the first symptoms in consumption being a loss of fat, caused by 

 a deficiency of carbon. The blood too of consumptive patients 

 is very thin and florid, showing a highly oxygenated condition 

 and deficiency of carbon ; and the best remedies are those rich 

 in carbon, as cod-liver oil, naptha and the like; and the respira- 

 tory tube acts beneficially, by retaining carbon in the lungs. 



But to return ; it may be asked, why the potato rot begins 

 in the cell wall ? Answer, because this part is required to hold 

 its contents during growth, and if deprived of its carbon, which 

 gives it firmness, it will burst, and from the breach arise the 

 fungi. 



Again, it may be asked, if the disease arise from defective 

 growth, why it ever attacks the potato after taken from the 

 ground ? Answer, the rot might be expected from a watery 

 potato of imperfect growth, or contagion might communicate it. 



Why sliould not species of vegetables pass away at this age, 

 as well as at a former one? They do and will, unless means 

 be applied for their preservation. 



But vegetables are not alone in passing away. Whole races 

 of animalSj of enormous growth, have become extinct, as the 

 mammoth, the mastodon, &c.. of whose former existence in our 

 own country there is abundant proof. 



Much carbonic acid has been abstracted by the growth of 

 vegetation, but more by carboniferous deposits. Every cubic 

 yard of lime is supposed to contain 10.000 cubic feet of car- 

 bonic acid gas. The quantity also in coal beds, containing 64 

 to 75 per cent, carbon, must be enormous, 



