2 THE SCIENCE AND PllACTICE 



grown for their roots have a peculiar aptitude for 

 laying on tissue, and thus increasing the bulk of their 

 "descending axis," that is, that portion of their 

 structure which grows downwards — root. Besides 

 this, they are remarkable for their capability of 

 producing varieties — a fact which, united with a 

 constancy in the maintenance of an induced form, 

 renders it exceedingly easy to bring out new sorts 

 which will maintain their characteristics under great 

 diversities of climate, soil, and treatment. 



The facility with which different sorts of roots 

 may be procured can readily be understood from the 

 many varieties, not only of turnip — which may 

 perhaps be considered as an original species — but also 

 of swede, which is a hybrid of the turnip and rape 

 plant. Of the former we have more than thirty sorts 

 grown by the farmer, and as many peculiar to the 

 garden ; whilst there are probably more than twenty 

 w r ell-recognized sorts of Swedes. Of beets, with 

 mangel-wurzel, we have almost as great a variety ; 

 so also of carrots. Of parsnips we have fewer varie- 

 ties, to which may now be added the new form called 

 the Student parsnip, the growth of which is so 

 interesting that we shall here give a short history 

 of its production, as an illustration of the origin of 

 root crops. 



In 1847 we collected some wild parsnip seed from 

 the top of the Cotteswolds, where this is among the 

 most frequent of weeds. This seed, after having 

 been kept carefully during the winter, was sown in a 

 prepared bed, in the spring of 1848, in drills about 

 eighteen inches apart. As the plants grew they w T ere 

 duly thinned out, leaving for the crop, as far as it 



