1914] Bryant: Economic Status of the Western Meadoidark 419 



plate. Great care was taken to see that every bit of the contents 

 was scraped from the walls of the stomach. A Zeiss binocular 

 was used in examining and determining the material found. 

 Where possible, counts were made of all vegetable and animal 

 elements of food. The amount of mineral matter used as grinding 

 material was computed by a calculation in per cent of the com- 

 parative volume. 



The comparative volume of each kind of food was calculated 

 in per cent of total volume contained in the stomach examined. 

 In the estimation of apparent volume there is always a personal 

 error. However, since this method is depended upon to furnish 

 evidence as to the comparative amounts and not actual amounts, 

 the personal error is largely distributed in the averages. Parts 

 of insects and weed seeds used in identification were wrapped 

 separately in small pieces of paper to prevent their mixing with 

 the rest of the stomach contents. 



Where possible, the heads of insects were used as a safe cri- 

 terion of the number eaten. In many cases dependence was 

 necessarily placed on an enumeration of the mandibles. In the 

 case of grasshoppers the mandibles are probably retained in the 

 stomach longer than the soft parts, but experiment has shown 

 that the stomach is completely emptied in four hours, so that 

 it is necessary only to give a long enough period of digestion 

 to make such an enumeration dependable. The fact that the 

 mandibles of grasshoppers may be found along the entire length 

 of the digestive tract also supports the view that this criterion 

 is trustworthy. Beetles, bugs, bees, and ants were readily 

 counted, because the heads and thoraces of these insects remain 

 long undigested. 



Partly digested grain and weed seeds were computed in per- 

 centage volume, but in addition the undigested kernels and seeds 

 were counted. 



Owing to the finely comminuted condition of the food to be 

 found in the intestines, that found in the stomach alone was 

 used as evidence of the food taken. The stomach alone gives 

 the best unit of volume. The consideration of the food to be 

 found in the intestines could at best but show evidence as to 

 food for a longer time previous to the death of the bird. 



