r 
512 QUEENSLAND AGRICULTURAL JOURNAL. [1 June, 1898. 
With regard to the practical application of the processes ot hybridisation 
and cross-fertilisation, in the prevention of special plant diseases, a few 
instances may be adduced :— ; 
As is well known, although the wheat plant suffers greatly from the so- 
called rust-fungi, and the injuries attendant on their development in its tissues, 
there are certain varieties of it that, although they do not perhaps enjoy an 
absolute immunity from the attacks of this destructive organism under every 
condition pertaining to their growth, are still highly resistant thereto. It has 
accordingly been conceived by investigators that this highly desirable quality 
might be conferred upon the progeny of classes of wheats not already possess- 
ing it by the adoption of artificial cross-fertilisation in which one or other of 
the resistant varieties was made to take part. Moreover, the project has not 
_only been entertained, but also acted upon. Especially has this been done by 
W. Farrer, of New South Wales (whose indefatigable labours in this direction 
are both widely known and appreciated), with the result that he has found not 
only that “the crossed seeds have always differed from the normal seeds of 
the mother variety by being larger,’ but also that “if we cross varieties of 
different types we find the progeny differing quite as much in the quality 
of resistance to either or both of these rusts —i.e., Puccinia dispersa 
and P. graminis)—as in any other quality, and that from such varying 
progeny there may generally be selected either plants which possess more or 
plants which possess less of the quality of resistance to either rust than does 
either of its parents ; further, that, by means of a system of cross-breeding of 
the above character combined with selection, varieties suitable for our climate 
which have been born with, and therefore possess—some of them in a higher 
degree than does either of their parents, as an attribute which is normal to them 
and stable in our climates—the quality of resisting the Spring Rust (Puccinia 
dispersa, Bricksson), can be and actually have been made; and that the varieties 
which resist the Summer Rust (P. graminis—‘ the rust which does the damage ’ 
—Farrer) are more numerous, and the degree in which they resist it more 
complete, than is the case with the spring rust. .I think from these data we 
may safely draw the conclusion that the making of varieties possessing 
suitability for our climate, in conjunction with sufficient ability to resist the 
summer rust, for our crops to be safe from serious (or, indeed, from any) injury 
by it is an easy matter, and only waitsfor its completion a few moist summers 
[that will render the performance of experiments on his part practicable— 
H.T.), even if the next rusty season does not show it has been actually 
accomplished already.’*—Op. cit., pp. 165-6. 
That which, as above related, has been accomplished by “ crossing” in pre- 
venting disease, in the case of the wheat plant, has been exceeded even with the 
vine. And the case of this plant is all the more interesting since true 
hybridisation has been resorted to, or the union through the agency of their 
sexual products of distinct species, and the results obtained are the labours of 
many independent workers, including Millardct, de Grasset, Condere and 
Ganzin, Castel, Franc, and Terras amongst their number. 
The questicn of preventing the attacks of phylloxera early engaged the 
attention of Millardet, and in the course of his investigations he foresaw a 
possible benefit {hat might accrue from raising hybrid progenies between vines 
such as Vitis rupestris and Vitis riparia, that were highly resistant to the 
attacks of the phylloxera, and the various varieties of the ordinary European 
Vitis vinifera that were so fatally infested by this notorious insect ; and sub- 
sequently he raised such hybrids, and, moreover, found that they were endowed 
with the desirable characteristics sought.+ And, again, others amongst those 
above mentioned experimented in the same direction, with like result. 
* K. Farrer: ‘The Making and Improvement of Wheats for Australian Conditions,” a paper 
read before the Australian Association for the Advancement of Science, 10th Jan., 1898.—Agr. 
Gazette of N.S.W., Vol. LX., 1898. 
+ Millardet : Notes sur les vignes Américaines. Ser. TIT. ssai sur Vbybridation de la 
iene Mem. de la Soc. des Sciences de Bordeaux, 1891. Ferner ; Journ, d’agriculture pratique, 
