15 



spread out evenly over the dish and examined with a pocket 

 ]ens ; for this purpose I prefer a Leitz No. 8, as it takes in a 

 wide field and does not magnify the larger objects beyond 

 recognition. With the larger birds it is often necessary to 

 wash the material in several lots of water, but with the smaller 

 birds this is risky and not to be recommended. As the objects 

 are identified they should be removed and. tabulated, and the 

 residue should be subjected to a careful microscopical examina- 

 tion. This is best done by placing a small quantity of the 

 material in a drop of clear water on a glass slide temporarily 

 protected with a covering glass. In many instances it will be 

 found necessary to float out the material on a piece of white 

 blotting or filter paper, and examine when dry under a low 

 power of the microscope. Whenever the insects or other 

 remains are sufficiently well preserved they should be counted. 

 This is often possible with the larger birds, such as Jays, &c., 

 but with the smaller birds the fragments are often so minute 

 as to render this impossible. The relative proportions of the 

 food can, in nearly all cases, be ascertained with some degree 

 of accuracy, and this should be noted as far as possible. 



ON THE RELATIVE VALUE OF BRITISH BIRDS IN 

 THEIR RELATION TO AGRICULTURE AND HORTI- 

 CULTURE AND IN OTHER ECONOMIC ASPECTS. 



In order to do justice to the subject matter under this heading 

 one ought perhaps to go much further afield than the facts 

 which are embodied in this memoir, as there is a considerable 

 amount of evidence available which would add materially to the 

 interest and value of this communication. On the other 

 hand, many of the contributors to the subject of the food of 

 British birds have been much too one-sided in their views, 

 either of praise or abuse ;, and a few have taken not the least 

 trouble to verify their own statements. On the whole, there- 

 fore, it has been thought desirable to offer this memoir solely 

 as a further contribution to the study of the exact nature of the 

 food of birds, especially in relation to Cheshire, and this has been 

 rigorously adhered to throughout. It is by no means an easy 

 task to group the birds together so that their relative economic 

 value can readily be seen and a standard of comparison 



