99 



others. The Rook, for instance, is a bird concerning 

 which It IS at present impossible to say whether it is a 

 benehcial or harmful species. It consumes a vast amount 

 of grain but, on the other hand, during the summ.er it 

 devours a great many injurious insects of various kinds, 

 jncludmg both leather-jackets and wireworms. The 

 Starling also devours a large amount of gram durm^j- 

 certain times of the year, but this appears to be com- 

 ]>ensated by the great quantity of injurious insects which 

 the bird consumes at other periods. As many as 197 

 leather-jackets, for instance, have been found by ]\Ir. 

 Leigh m the crop of a single bird. The Chaffinch is by 

 no means as destructive as is commonly believed. It 

 consumes large quantities of seeds of such troublesome 

 weeds as, dock, knotgrass, hawkweed, and especially 

 chickweecl. Mr. Leigh informs me that although he 

 found grain m the crops of 41 per cent, of the birds which 

 he examined, it appeared to have been taken m most cases 

 from manure or ricks m farmyards and not from culti- 

 vated land. It must be further added that evidence 

 points to the fact that the majority of species of birds 

 feed their nestlings on soft-bodied insects and other 

 invertebrates. Consequently even the most destructive 

 birds may perform a useftil function during that stage in 

 their life. 



EelwoRMS '4 , '5 ., belong to the group of the Xema- 

 toda. They are always small in size and have thread-like 

 bodies, the two ends being more or less pointed. They 

 can be readily distinguished from the Oligochaeta or 

 Earthworms by the total absence of body rings or seg- 

 ments. Those which are plant parasites are microscopic 

 forms living free 111 damp soil or mside the tissues of 

 plants. Others live m decaying vegetation, and both the 

 parasitic and saprophytic forms can be recognised by the 

 presence of a spme which can be proirucled through the 

 mouth and serves to penetrate the cell-walls of plants. 

 The Eehvorms spread from one plant to another by 

 wandering through the soil, and when they leave the dead 

 plants they lie near the surface of the ground. Fre- 

 quently when these animals are numerous it is useless to 

 grow susceptible plants m the same patch of soil during 

 successive seasons, and then as long an interval as possible 

 should elapse between the growing of two crops of the 

 same plant. The STEM Eelworm {T ylenchus dei astatrtx,. 



