30 
HISTORICAL PART 
of forestry to shorter circuits not only transformed the life 
of insects but had an effect on the conditions of life of birds 
too, particularly by depriving the birds of most value to 
forestry and agriculture of opportunities of nesting, above 
all by taking away the hollows." 
„The intensive cultivation of the regained territory trans- 
formed the conditions of life of lower-grade animals too. 
As the quantity of each product increased, the number and 
quantity of its enemies increased also." 
,-The essential point of the whole transformation, as far 
as the relation between animals and the vegetable world is 
concerned, may be concisely expressed as follows: the in- 
creased dimensions of production naturally increased the 
number of organisms living on the products, while on 
the other hand the work of extermination and transfor- 
mation deprived all those organisms (from the point of view 
of this sketch birds), which are prime factors in the pro- 
tection of the products, of chances of nesting and conse- 
quently of propagating, in fact of subsistence." 
Though this part of the report is a reflection of the state 
of things in Hungary in particular, there is no doubt that a 
similar state of things exists, more or less, in the other 
countries of our zone: it is moreover to be taken as con- 
cerned more particularly with those species of birds which 
are permanent inhabitants of the respective districts, i. e. do 
not depart for winter. 
As for the birds of passage, the report continues as follows: 
„The case of those birds useful to agriculture, which in 
winter leave the temperate and northern regions to hibernate 
in the districts of the torrid zone, returning only in spring, 
is quite different." 
„ During the departure and return they fly over various 
zones, pass through many countries, and, apart from the 
