402 PERNS NOT ATTACKED BY INSECTS. [April, 



vated Brassica, according to the received opinion. In the next 

 place^ it is difficult to see why man may not have existed at firsts 

 or even for a length of time, without either a well-hearted cabbage 

 or bread-corn for his food : certain it is that the leaves of Sea 

 Cabbage make a good and palatable dish of greens : and, further, 

 the accredited account is usually thought to imply that man had 

 no acquaintance with bread -corn until he was condemned to 

 labour. 



Besides, it is not certain that our cultivated kails and coles, 

 etc., are all derived from the same wild plant, for De CandoUe 

 inclines to think that several wild species of Brassica were taken 

 into cultivation in different countries, and that this may help to 

 account for the existence of so large a number of garden varieties. 



But the Brassica and jEgilops are improperly classed together 

 when the proofs of the latter passing into wheat are as much dis- 

 puted as the transformation of the former is accepted. And if 

 we may believe that corn, scarcely distinguishable from cultivated 

 sorts, has been found really wild in various parts of Asia, the 

 j^gilops question will lose much of its importance, as its trans- 

 mutation into wheat becomes less credible. 



A. 



Why Ferns should not be attacked by Insects. 



One of your correspondents, S. B., inquires (p. 370) if there is 

 any reason why Ferns should not be attacked by insects ? I had 

 frequently observed how seldom the fronds of Ferns were dis- 

 figured by insects, both in the field and herbarium, and the pro- 

 perties detailed below seem to explain the circumstance most 

 satisfactorily. 



Ferns possess an active principle, consisting of a volatile oil 

 and resin, which has destructive effects upon some of the radiate 

 and annulose animals. Since the time of Dioscorides the Male 

 Fern has been celebrated as a vermifuge. The rhizome, in the 

 form of powder or decoction, was usually exhibited-, and probably 

 the root- stocks of all the common species, as at the present time, 

 were collected by herbalists. Like many other valuable indi- 

 genous remedies, this fell into discredit from the large dose re- 

 quired, the uncertainty of the preparations employed, and the 



