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The saccharine matter in the cotyledons at th,e 

 time of their change into seed-leaves, renders them ex- 

 ceedingly liable to the attacks of insects : this princi- 

 ple is at once a nourishment of plants and animals, 

 and the greatest ravages are committed upon crops in 

 the first stage of their growth. 



The turnip fly, an insect of the colyoptera genus, 

 fixes itself upon the seed-leaves of the turnip at the 

 time that they are beginning to perform their func- 

 tions ; and when the rough leaves of the plume are 

 thrown forth, it is incapable of injuring the plant to 

 any extent. 



Several methods have been proposed for destroy- 

 ing the turnip fly, or for preventing it from injuring 

 the crop. It has been proposed to sow radish-seed 

 with the turnip-seed, on the idea that the insect is fon- 

 der of the seed-leaves of the radish than those of the 

 turnip ; it is said that this plan has not been success- 

 ful, and that the fly feeds indiscriminately on both. 



There are several chemical menstrua which ren- 

 der the process of germination much more rapid, 

 when the seeds have been steeped in them. As in 

 these cases the seed-leaves are quickly produced, and 

 more speedily perform their functions, I proposed it 

 as a subject of experiment to examine whether such 

 menstrua might not be useful in raising the turnip 

 more speedily to that state in which it would be se- 

 cure from the fly ; but the result proved that the prac- 

 tice was inadmissible ; for seeds so treated, though 

 they germinated much quicker, did not produce 

 healthy plants, and often died soon after sprouting. : 



c2 



