2 Transactions. — Miscellaneous. 



on the undergrowth, wliich is still further injured by the 

 depredations of Cbittle ; gradually the plants less able to resist 

 changed conditions disajapear, and with them many insects, 

 lizards, and birds, which are unable to obtain then- usual food 

 in the new environment. 



But the space occupied by the displaced plants is not 

 long allowed to remain unoccupied. An army of encroaching 

 weeds speedily takes possession of the vacancy : thistles, star- 

 thistles, docks, groundsels, brambles, briars, and a hundred 

 other unattractive invaders make their appearance, and in- 

 crease the severity of the struggle for the survivors of the 

 indigenous flora. From sea-level to the highest points reached 

 by the miner or shepherd, from the North Cape to the Ant- 

 arctic Islands, their hosts press forward, ever seizing some 

 new position, just as on a larger scale they have long since 

 occupied the vicinity of the chief ports on the great lines of 

 ocean travel from Britain to the Cape of Good Hope, from 

 Yokohama to Cape Horn, so that wherever the traveller 

 lands from his floating home he finds himself surrounded by 

 familiar plants which have in a greater or lesser degree amal- 

 gamated with the vegetation of the country which they have 

 invaded, and which to a large extent they will ultimately over- 

 come. 



And, most unhappily, this invasion is not restricted to 

 phanerogamic plants. Numbers of injuinous fungi accom- 

 pany their hosts. Eust, mildew, and bunt blight the hopes 

 of the wheat-grower at the moment of fruition. The grazier 

 too often sees his pastures rendered useless by the ravages 

 of smut and ergot ; while the cultivators of edible fruits and 

 vegetables can point to special enemies of almost every kind 

 of plant grown for its value as an article of food. Nor is this 

 all. Numbers of species, almost equally insidious in their de- 

 velopment, are parasitic, not only on members of the indi- 

 genous flora, but on the naturalised weeds themselves ; so 

 that the circle of infection is constantly widening, while the 

 scientific knowledge and practical skill of the cultivator are 

 taxed to the utmost limit. 



Further, the invading army of plants has brought in its 

 train a still more dangerous host of animals ; and as in the 

 vegetable kingdom the most injurious forms were found 

 amongst the less highly organized kinds, so in the animal 

 kingdom the invaders whose agency is most dreaded are 

 members of the Invertebrata : the mussel scale, the fluted 

 scale, the black scale, and many others, together with 

 numerous species of plant-lice, will occur to you as belong- 

 ing to lowly-developed forms of Insecta. Higher in the 

 scale, the Hessian fly, wire-worm, turnip-fly, and others ; 

 while numerous species of earth-worms, molluscs, birds, 



