328 
POPULAE SCIENCE EEVIEW. 
on the nature of the locality^ whether favourable or otherwise ; 
and wherever a complete or only partial failure of food has 
taken place^ so accordingly will the species depart or remain. 
Moreover^ what has just been remarked in connection with 
the stone-chat, might be applied again to the robins and 
thrushes of Southern Europe : supposing one of either hatched 
in Italy, and after several years^ migrations to the oasis of the 
desert, should deviate on one occasion from its accustomed 
course and fly northwards, and spend the winter in Northern 
Europe, — ^with the example of the resident individuals before 
it, no doubt the robin would soon pick up crumbs at the 
kitchen door, and the thrushes crowd with their indigenous 
brethren on the holly-trees, and, becoming climatised, remain 
in their adopted countries ever afterwards. Although we have 
no direct proof that such occurrences actually take place, there 
is nothing in the bird^s constitution to preclude such a sup- 
position; and not only that, but we know in the case of 
Pallas^ s sand-grouse, and many other accidental visitors, that 
they have at once adapted themselves to the food afibrded by 
the country, although perfectly new to them. How far such 
influences, acting on generations and for long periods, do 
affect the external appearances or internal structure of a 
species, are points not yet clearly determined ; but doubtless, 
as the geographical distribution and migrations of animals 
become better known, so will many diflS.culties of that nature 
be cleared up. Of the vast hosts of birds that cross the 
Mediterranean annually, not a few perish on their way, and 
their bodies are thrown up on the beach ; many arrive only to 
die, as we can testify from our own observations along the 
shores of Malta, where we have picked up numerous warblers 
that had been either drowned on their passage or died on the 
rocks, or had dashed themselves at night against the fortiflca- 
tions and lighthouses. 
“ The beacon blaze illures 
The bird of passage, till he madly strikes 
Against it, and beats ont his weary life.” 
The quail on its way to Europe in spring, or Africa in 
autumn, is often borne back by a strong head wind to the 
country it had just left ; and we have repeatedly noticed that 
a strong sirocco in September scarcely ever fails in throwing 
abundance of quail on the south-east coast of Malta, in the 
same way that a powerful gregale brings in many that had 
been bent on an opposite direction. We now come to observe 
that extraordinary intelligence whereby swallows, for instance, 
are enabled year after year to return to the same nest. Taking 
into consideration the long absence, the dangers and difflcul- 
ties incident to the voyage, it seems incredible that any animal 
not human can be capable, after nearly eight months^ sojourn 
