494 THE GANNET 



while in the nest, which is said to be sometimes three inches 

 thick upon the breast.* A half -grown young one weighed 

 7 lb. 8 oz., an older juvenile 8 lb. 4 oz., whilst one which was 

 ready to take the sea, weighed 8 lb. 12 oz. ; all three were 

 alive when \i^eighed. As their fat melts away so do they 

 decrease in bulk, but it takes a long time to work it all off. 

 A young one, which could fly well enough to get as far 

 south as Norfolk, weighed on October 23rd, 5 lb. 8 oz., 

 having got rid of 3 lb. in about six weeks, supposing that 

 it had left the Bass about September 11th {see p. 375) f 



The Pterylosis or Feather-tracts. — The feather-tracts or 

 patches in birds' plumage vary much in different families, 

 and, there can be little doubt, have relation to the 

 movements of the body and the wings ; as they are 

 usually well-defined areas, they are held by naturalists 

 to be of primary importance. The first to make a 

 serious study of this previously neglected subject was 

 Christian Nitzsch, an original investigator, who in 



* "St. Kilda," by G. Setoii, p. 181. 



f In the " Field " of September 16th, 1899, there is an article on the 

 weights of various large birds, by Mr. J. E. Harting, who also gives a good 

 many weights in his " Handbook of British Birds " (new edition). Mr. M. 

 Barne tells me that some of the Emperor Penguins which he assisted 

 Captain Scott to collect in the Antarctic, weighed over 80 lb., a figure 

 which no Eui'opean bird approaches. 



