W. Travers.—On the Spread of Cassinia leptophylla. 249 
it affected the pastoral occupiers, the results of which I will mention in the 
sequel I have, moreover, heard that this plant is already interfering greatly 
with the use of the natural pastures on the east coast of the North Island, 
more particularly within the Wellington Province; and that sheep-farmers 
there are looking upon its presence as a very serious and not easily preventible 
evil. But before mentioning the results of my enquiries in regard to it, I 
propose to notice a few interesting facts, most of which have come under my 
own observation, in connection with what Dr. Hooker has termed the 
“replacement of species,” a term used by him to designate the permanent 
changes which take place in the flora of a new country, as the result of the 
introduction of competing foreign organisms. The facts which I purpose 
mentioning, however, though properly associated with such permanent effects, 
relate only to certain оротат саа in the character of the introduced 
vegetation, not brought or by the direct application of labour. 
In former papers, read before ibis Society, I pointed out that accli- 
matization (a term, by the way, which I object to as involving a fallacy, and 
which I think ought to be replaced by * naturalization"), or the introduction of 
foreign organisms into a country presenting suitable conditions for their 
growth and subsistence, is the result of both intentional and unintentional 
action on the part of man. His intentional action is usually directed to the 
attainment of beneficial ends, but is constantly accompanied (unavoidably to a 
certain extent) by mischievous results. Of these latter I may instance the 
introduction of various forms of Coccus and Aphis; and of the larve of various 
species of destructive Coleoptera and Diptera, most of which have been 
brought in Wardian cases; and of the seeds of innumerable weeds, such as 
those of Rumex, Stellaria, Hypocheris, Euphorbia, etc. I also pointed out the 
results which are usually produced upon the indigenous vegetation in countries 
previously unoccupied by civilized man, by the introduction of animals and of 
competing foreign organisms. 
It must not, however, be supposed that the struggle thus brought about 
. between the introduced and indigenous forms of life is а mere battle between 
these two forces, for, in reality, each individual species concerned, whether 
. local or foreign, is fighting “on its own hook,” striving against all as against 
a common enemy, and seeking to secure for itself the greatest share in 
ultimate occupation, As may be understood, many of the combatants, if not 
altogether disabled, are seriously enfeebled, whilst the fortunes even of those 
which are able to show the strongest front are somewhat various. Now, w 
know that in the hill districts of both islands of New Zealand the chief ы 
of the European settler is to replace the native vegetation by grasses suitable 
for the maintenance of cattle and sheep, and various processes, more or less 
direct in their action, are employed in order to attain this end. 
Pl 
