discriminative death which the theory of Natural Selection 
presupposes. 
We cannot doubt for one moment that in certain cases 
the increase of animals and plants is sometimes enormous. 
This phenomenon is most obvious in connection with 
animals or plants which have immigrated into a country 
where the conditions are favourable to their well-being. 
The wild bees which now exist in millions in New Zealand 
are the offspring of two or three hives, which were once 
kept in the rooms of Cotton, of Christ Church, Oxford, 
and were taken over by him when he went to New Zea 
land with Bishop Selwyn. Some years ago fifty sparrows 
were sent to the same colony in the hope that they would 
increase and multiply and keep in check the insects which 
were so troublesome to the agriculturist. They have in 
creased to an enormous extent, but they have changed 
their food ; and the farmer has found in them foes even 
more terrible than blight or caterpillar. The sweet-briar, 
taken by a missionary to his Australian home, has flourished 
in a surprising manner, turning a cleared farm into an 
impenetrable thicket, and has to be torn out with cart- 
ropes and teams of horses. A Scotch emigrant took with 
him to Australia a thistle in a flower-pot. It was carefully 
transferred to the soil, and its growth was affectionately 
watched by the exiles from Caledonia. But soon the land 
was covered with monstrous thistles, which defied attempts 
at extermination. 
“ Columbus, in his second voyage, left a few black cattle at 
St. Domingo, and these ran wild and increased so much, that 
twenty-seven years afterwards herds of from 4000 to 8000 head 
were not uncommon. Cattle were afterwards taken from this island 
to Mexico, and to other parts of America, and in 1587, sixty-five 
years after the conquest of Mexico, the Spaniards exported 64,350 
hides from that country and 35,444 from St. Domingo. 
In the pampas of Buenos Ayres there were, at the end of the last 
century, about twelve million cows and three million horses, besides