56 TRACTS ON VARIOUS SUBJECTS, &c. 



property of being- unmolested by an insect (I believe the dolphin 

 fly) which is here extremely destructive to cabbages, turnips, and 

 radishes. I have very often observed, where alternate plants of 

 cabbage and mangel wurzel were growing in the same rows, and 

 touching each other, that whilst the former were absolutely anni- 

 hilated by that destructive insect ; not one was to be seen on the 

 mangel wurzel leaves. This extraordinary circumstance seems 

 to favour Lord Bacon's notions (however much they have been 

 exploded) that some insects " breedeth of dew and leaves in 

 " spring ; and commonly when the East winds have much 

 " blown — the cause whereof is, the dryness of that wind ; for, to 

 " all vivi/ication upon putrefaction, it is requisite the matter be 

 " not too moist." 



But, whatever may be the origin of those insects, it is of little 

 consequence to the present subject. I have merely stated a fact, 

 which may possibly attract notice, and may be of some use to those 

 who are engaged in the contemplation of matters of this nature. 



The mangel wurzel, when fairly established in the soil (which, 

 like every other crop upon an extensive scale, ought to be just 

 before the expected rains in January and February, or in July 

 and August), will soon acquire such vigour as to become almost 

 independent of rain : for having a tap root, penetrating 12 to 18 

 inches, or more, into the soil, it will always find sufficient mois- 

 ture, at that depth, for carrying on the process of vegetation. In 

 the course of five or six months, from the seed, if sown or planted 

 in good soil, three cuttings of the leaves may be obtained, which 

 may average about three pounds from each plant ; and the roots 

 will then have attained the weight of five to ten pounds each. 

 AVherefore it seems to me, after every attention I have given this 

 subject, that the most profitable culture would be to take three 

 cuttings of the leaves, and at the third cutting, to dig up the 

 roots: — the,se, as well as the leaves, afford a nutritious food for 



