206 ANIMALS AT WORK AND PLA Y 



generalisation. The birds are guided by some 

 faculty not yet understood, and our daily-growing 

 acquaintance with the facts of migration does not 

 in the least diminish the difficulty of its discovery.* 



* Slatin Pasha's history of his captivity among the Dervishes contains a 

 notable instance of the identification of a migrating crane. He was summoned 

 before the Mahdi and his cadis, and asked to account for some writing inside a 

 brass case attached to a ring. The paper contained a note written minutely in 

 four languages, stating that this crane was hatched on a certain estate in South 

 Russia, and asking anyone into whose hands it fell to communicate with the 

 writer, whose name and address were given. The Mahdi then said that the case 

 had been found fastened to a crane which was shot at Dongola in December. The 

 date of the letter it bore was September, 



