PART n. 



On the Study of Species, considered as to their Origin, 

 their early Cultivation, and the Principal Facts of their 

 Diffusion.^ 



CHAPTER L 



PLANTS CULTIVATED FOR THEIR SUBTERRANEAN PARTS, 

 SUCH AS ROOTS, TUBERCLES, OB BULBa^ 



Radish. — Raphanvs sativus, Linnaeus. 



The radish is cultivated for what is called the root, 

 which is, properly speaking, the lower part of the stem 

 with the tap root.^ Every one knows how the size, shape, 

 and colour of those organs which become fleshy vary 

 according to the soil or the variety. 



There is no doubt that the species is indigenous in 

 the temperate regions of the old world ; but, as it has 

 been cultivated in gardens from the earliest historic 

 times, from China and Japan to Europe, and as it sows 



' A certain number of species whose origin is well known, such as 

 the caiTot, sorrel, etc., are mentioned only in the summary at the begin- 

 ning of the last part, with an indication of the principal facts concerning 

 them. 



2 Some species are cultivated sometimes for their roots and some- 

 times for their leaves or seeds. In other chapters will be found species 

 cultivated sometimes for their leaves (^as fodder) or for their seeds, etc. 

 I have classed them according to their commonest use. The alpha- 

 betioal index refers to the place assigned to each species. 



* See the young state of the plant when the part of the stem below 

 the cotyledons is not yet swelled. Turpin gives a drawing of it in the 

 An,nales des Sciences Naturelles, series 1, voL xxi. pi. 5. 



