208 THE AUSTRALIAN NATURALIST. 
out special manures, they may lose their distinctive char- 
acter which originally distinguished them from the rest; this 
is what is known as “‘atavism,’ or the reversion to its ances- 
tral or primitive form. 
When a special kind of rose or tuber has been produced 
by artificial means, it is not always possible to reproduce it 
from seed, so that in such cases it has been found necessary 
to propagate by budding or grafting on special stocks, or by 
striking from cuttings, or in tubers or herbaceous plants, by 
_ dividing them into ‘‘sets.’’ It will be gathered from the 
above that what is frequently known as variation is in reality 
a process of evolution, which is more rapid when aided by 
artificial means, than is the case in a state of Nature. 
In Australian plants there is the same tendency to vary 
as in those mentioned above. <A few examples worthy of 
special mention, are as follows:—The Native Rose (Boroma 
serrulata) has normally bright red-coloured flowers, but I 
have seen specimens having pure white flowers. : 
Patersonia sericea, has usually bright blue-coloured flow- 
ers, but some few years ago I gathered a specimen with a pure 
white flower, growing at Hornsby. ast year, a Waratah 
(Telopea speciossima) was brought in the National Herbar- 
ium, having pure white flowevs instead of the usually bright 
crimson. 
Letratheca thumifolia, and Hriostemon salicifolius, have 
frequently been collected with white flowers 
Another peculiar form of variation worthy of mention 
is a fairly common fern (Blechnum cartilagineum), which 
had the fronds beautifully bi-pinnatifid instead of simply pin- 
natifid. This I found growing near Cundletown on the Man- 
ning River, specimens are incorporated in the National Her- 
barium. In Hurope, protessional horticulturists would take 
advantage of these interesting forms, and would propagate 
them extensively, so as to perpetuate them with a view of 
getting further variations. : 
Dimorphic and Polymorphic Forms.—In addition to the 
variations mentioned above, we frequently find certain species 
chaving two kinds (Dimorphic) of flowers, and others having 
several (Polymorphic) kinds of flowers or other characters. 
An example of this kind has recently been brought under 
notice by T. Steel, F.L.8., who has published an interesting 
paper entitled “Notes on Variable Dioecism in Pitiosporum 
undulatum,’’ in the proceedings of the Linnean Society of 
N.S.W. (1911), p. 329. 
This is an unusual form of dioecism, as each kind of 
flower has a pistil, but the individual plants which set fruits 
have apparently almost obsolete stamens, while those flowers 
that have perfect stamens do not set fruits, although the ovar- 
