134 Experiments with Calcium Cyanamide. [may, 



results were available from 141 specimens examined by Mr. 

 Douglas T. Thring at intervals of a few days throughout 

 1908, in addition to the records of 58 specimens previously 

 dissected by Mr. Collinge. A summary of the results from 

 these 830 birds showed that 67*5 per cent of their food con- 

 sisted of grain, 3*5 per cent, of seeds, fruit, roots, and mis- 

 cellaneous vegetable matter, 15 per cent, of wireworms and 

 other insects, io"5 per cent, of earthworms, and 3*5 per cent, 

 of miscellaneous food (eggs, young game, field mice, &c). 

 There is ample evidence, therefore, to show that with the 

 present large numbers of rooks a grain diet is preferred, and 

 also, so far as this inquiry goes, that the rook is not a par- 

 ticularly beneficial bird to the agriculturist, although its 

 usefulness might be considerably increased were it fewer in 

 numbers. The recommendation, therefore, which Mr. 

 Collinge makes is to the effect that land agents and others 

 should at once proceed systematically to reduce the existing 

 number and to hold it in check. 



The supply of artificial nitrogenous manures has been 

 increased during the past year or two by the introduction on 

 a commercial scale of the two new 



Experiments with fertilisers, viz., nitrate of lime and 

 Calcium Cyanamide calcium cyanamide. Articles on the 

 and Nitrate of Lime. use Q f these manures have appeared in 

 the Journal from time to time, and the 

 results of a number of experiments have been included in the 

 monthly summary. 



The general tendency of the results obtained seems to be 

 that the effectiveness of the nitrogen contained in nitrate of 

 lime or in calcium cyanamide is approximately equal to that 

 of nitrate of soda or sulphate of ammonia, but that on certain 

 soils the lime which the new fertilisers contain gives them 

 an advantage, and may make either of them more suitable. 

 Thus in experiments carried out by the Royal Agricultural 

 Society at Woburn, in which a comparison was made between 

 sulphate of ammonia and calcium cyanamide as a top-dressing 

 for barley, the results were greatly in favour of the cyanamide. 

 The Woburn soil, however, is decidedly deficient in lime, 

 and the better crop obtained was attributed in a large measure 



