152 UNSOLVED PBOBLEMS. 



of coming events. Thus certain birds and other animals 

 appear to know when a given district or country is becoming 

 infected with epidemic disease, in which case they leave or 

 avoid the infected district or country till the epidemic has 

 disappeared. This has been specially noticed prior to out- 

 breaks of such diseases as cholera in man. In the autumn 

 of 1874 a paragraph taken from a foreign (German) journal 

 called the ' Jardin Zoologique,' and relating to supposed or 

 alleged foresight in birds, went the round of British medical 

 journals and newspapers. It stated that 6 a few days previous 

 to the terrible ravages of cholera in Galicia in 1872 all the 

 sparrows suddenly quitted the town of Przemysl, and not a 

 single bird returned until the end of November, when the 

 disease had entirely disappeared.' 1 'The same circum- 

 stance was remarked in Munich and in Nuremberg. During 

 the attacks of cholera at St. Petersburg and Riga in 1848, 

 in Western Prussia in 1849, and in Hanover in 1 850, every 

 swallow and sparrow forsook the towns, and remained ab- 

 sent until the eradication of the scourge.' 2 In various con- 

 tributions to the ' Natural History of Cholera,' published 

 nearly a quarter of a century ago, 3 I gave other similar in- 

 stances of the apparent influence of the epidemic cholera 

 poison on a considerable variety of animals. In all such 

 narratives it is obviously necessary, in the first place, to 

 determine whether the coincidence is as stated whether it 

 be a fact that sparrows, swallows, jackdaws, or other birds 

 or animals do desert cholera-stricken towns or districts prior 

 to the outbreak of the epidemic in man and in the next 

 place we have to assure ourselves that the coincidence, if 

 proved, is not merely accidental, but has occurred so fre- 

 quently under the same or similar circumstances that some 

 relationship of cause and effect must be admitted. Assum- 

 ing that the coincidence has been indubitable and frequent, 

 the only sort of foresight or prescience that at present we 

 can safely ascribe to such cautious animals is of the same 

 kind as that which enables them to forecast weather change. 



1 < British Medical Journal,' vol. ii. for 1874, p. 312. 



2 < Daily Keview ' (Edinburgh), August 31, 1874. 

 * Vide Bibliography. 



