50 



COURSE OF THE SAP. 



PT. II. 



air ; and under this idea tlie soil is twice hoed after 

 the potatoes are above it ; that is, it is ' flat hoed ' and 

 ' hilled up.' And Liebig himself says : ' The increase 

 of crops obtained by the use of guano is very remark- 

 able. According to the same authority (Garcilaso), 

 the crop of potatoes is increased forty-five times by 

 means of it,' and ' I applied to a field of potatoes 

 manure consisting of night-soil and sulphate of mag- 

 nesia (Epsom salts), and obtained a remarkably large 

 crop.' Again : ' In the first year all the different parts 

 of the field produced potatoes, but they succeeded best 

 in those divisions which had been manured with peat, 

 ashes, lime, and marl.' All these cases prove the 

 growth of the potato to be from the soil, not from the 

 air. 



If plants draw their nourishment from the atmo- 

 sphere, why do we find plants peculiar to peculiar 

 soils ? Let any one farm on the idea that the growth 

 is to accrue from the atmosphere, not from the soil. 

 If Liebig's views are correct, a landlord should put his 

 land up to let, not by the quality of the land, but by 

 the acreage of atmosphere which overhangs the land. 

 If, however, Liebig would but condescend to follow the 

 example of Dioclesian, and plant chemical kale instead 

 of imperial cabbages, he would find that he must not 

 leave the large leaves on his transplanted greens with 

 a view of supporting the plants, but that he must cut 

 the large leaves off because the plants cannot support 

 them. 



