DR. BUREAU ON THE PARTRIDGE. 211 



and that the innermost primaries grow rather more 

 rapidly than the outer ones. 



4. The progress of the moult is the same within 

 certain very narrow limits, both in birds of the same 

 covey and in birds of different coveys of the same 

 age. 



5. The moult and growth of the primaries appear 

 to stand apart in the matter of regularity from 

 all the other processes of development, e.g. the 

 bird's weight bears no constant relationship to this 

 or to any other part of its development. 



METHODS OF STUDY. 



In the first place the author obtained his general 

 ideas by studying the growth of hand-reared birds, but 

 he is careful to say that he has made use of no facts so 

 acquired that were not afterwards confirmed by means 

 of wild-birds. 



Secondly, he gradually compiled what he has termed 

 his " Table of Moult," showing the daily growth of 

 each feather up to the time when the one external to 

 it was shed. This he did by shooting individuals from 

 coveys of unknown age at known intervals of time, until 

 he had acquired such a large number of observations 

 and measurements that it was safe to deduce averages 

 for each primary. 



Thirdly, he had certain nests marked, and their date 

 of hatching noted, so that wild-bred coveys of absolutely 

 known age could be watched and individuals killed 

 from them at specified intervals. By means of these 

 he was able first of all, to fix what he calls the " zero- 

 point," i.e. the exact age at which the tenth primary 

 is dropped, and secondly to apply " controls " of known 

 age to his " Table of Moult," and to compile finally 

 what he terms his " Chronometric Table," which 

 shows the day on which each primary is shed, and 

 the daily growth of each feather up to the time its 

 external neighbour is dropped. By using this table 

 any one can tell, within a day or two either way, the 

 age of any bird that he happens to shoot up to an age 

 of 116 days, i.e. until the third primary is fully grown, 

 the bird being then practically also full grown, and 



