98 THE SCOTTISH NATURALIST 



130 Species of Birds have been set free, of which 25 are 

 naturalised, including Pheasants, Quail, Little Owl, Skylark, 

 Song Thrush, Blackbird, Hedge-Sparrow, Rook, Starling, and 

 Goldfinch ; and, in addition, many fishes, snails, and insects, 

 and over 600 species of plants are now more or less truly wild. 



Where the introduced animal or plant took to the new 

 land, two striking processes followed : there was sometimes 

 a marked increase in size — Scottish Red Deer carried up 

 to twenty points on their antlers, Trout broke all Old World 

 records for size. Common Water Cress grew 12 to 14 

 feet long, and the Common Spear Thristle formed thickets 

 6 to 7 feet in height ; and there was often a remarkable 

 increase in numbers — Rabbits became an intolerable pest, the 

 Vulpine Phalanger, introduced in 1858, so multiplied that 

 in 191 2, 60,000 skins were sold (at 8s, to los. each) from 

 one district alone. 



But on the whole the introductions have not been a 

 success. The Rabbit pest and the destruction caused by 

 Stoats and Weasels have become by-words. Since Thrushes 

 became established garden fruit has had to be netted ; and 

 indeed of all the birds introduced, only one has escaped 

 criticism — the Hedge-Sparrow. The establishment of Trout 

 is regarded as the most successful of the ventures ; but even 

 it is responsible for the decrease of native fishes, for the 

 wholesale destruction of aquatic insect larvae, and for the 

 consequent diminution of the birds which largely depended 

 on that particular insect food. 



To onlookers the lesson is clear. The ultimate effect 

 of an introduction is hard to gauge ; but the result is 

 generally harmful. The setting free of foreign animals 

 ought, then, not to be left in the hands of this or that 

 enthusiast whatever be his object ; enlightened countries 

 will come to see that naturalisation must be prohibited 

 by law, to be permitted only after every aspect of each 

 separate problem has been considered by those most com- 

 petent to judge — namely, the biologists. 



* * * * 



By the recent issue of the i8th and 19th parts of Die 

 Vogel der Paldarktischeu Faiina, a work of great interest to 



