1 June, 1898.] QUEENSLAND AGRICULTURAL JOURNAL. 515 
placed in pure cultivations of different micro-organisms, notwithstanding they 
are practically insoluble in the media of these cultivations, inhibit or prevent 
the growth of these organisms in a very marked manner; and in the absence 
of any suggested explanation of this phenomenon it may be presumed that a 
germicidal action by infinitesimal quantities is being displayed.* 
The introduction of metallic salts into the tissue of plants, moreover, forms 
the special feature ina treatment employed in France, with—in some instances 
—marked success, in obviating the previously mentioned vine disease chlorosis, 
and known as “ Badigeonnage Rassiguier.” ‘This treatment consists in applying 
to all the fresh surfaces exposed by the pruning scissors or “secateur”’ a strong 
solution of sulphate of iron, at a time when there is free movement of the sap 
(z.e., in October, in France). The absorption (states Rassiguiert) in this case 
takes place rapidly ; and, after some days have elapsed on cutting a “courson” 
or a “bras de souche,” it is easy to detect traces of sulphate of iron by following 
up the tissue of the plant. In fact, according to L. Degrully, this solution can 
be observed to penetrate into the body. of tlie branch from 10-12 centimetres 
below the point of insertion of the shoot through which the solution has 
entered. ‘The benefit foliowing the adoption of this process of inoculation has 
been fully dealt with by the last-mentioned authority,{ and would appear to be 
very pronounced. 
From the foregoing statements it would seem likely also that there may, 
after all, be some grounds for concluding that the observed freedom from 
disease, said in some instances to follow the act of driving metallic’ nails into 
the wood of fruit trees, may stand in the relation of cause and effect. 
With regard to other forms of inoculation for preventing disease in plants 
it may be remarked that, though those maladies that might be attributable to 
the presence and action of bacteria have been little studied, “there are (to 
quote Dr. Erwin F. Smith) in all probability as many bacterial diseases of 
plants as of animals.’ Moreover, with regard to the bacteria that produced 
maladies in plants, it may be further affirmed that they are closely related, 
both biologically and morphologically, to bacteria that produce maladies in 
animals. Again, in the course of their growth they both may produce acids, 
alkalies, enzymes, or other bodies. Thus, whereas in the case of animals 
immunity may be secured by inoculating into their systems products derived 
in the course of their development from pathogenetic bacteria, so also the 
same may happen when similar inoculation is performed on plants, and this 
seems especially probable since it has been demonstrated that the disease itself, 
with its casual agents, can be communicated to them by this procedure. 
As to the employment of any method of inoculation related to that which 
consists in the use of serum, as in dealing with animal diseases occasioned by 
micro-organisms, it may be stated that, although Dr. Russell has concluded 
from experimental evidence that “vegetable cell juices, aside from their acid 
reaction, are entirely powerless against bacteria, and do not possess any 
germicidal properties like the blood serum of animals,’§ the experiments 
that he conducted were “too limited in number to afford any basis for a 
general conclusion”; and there are grounds for concluding that “it is not 
improbable'that a great variety of bactericidal and protective substances occur 
in plants,’ just as there are bodies contained in them, such as “the various 
essential oils and other vegetable products—e.g., thymol, salicylic acid, benzoic 
acid, tannin, quinine, oil of cinnamon, oil of peppermint,” &c., that are known 
to “exert a powerful restraining influence on bacterial growth.”|| 
* Dr, Meade Bolton: ‘The Effects of various Metals. on the Growth of certain Bacteria.” 
‘‘Tnternational Medical Magazine,” December, 1894. 
+‘ Progress Agricole,” 28th August, 1892. 4 
+L. Degrully : “Traitement de la Chlorose.”—Montpellier, 1894, . 
§ Russell: “Bacteria in their Relation to Vegetable Tissue.” Thesis. Johns Hopkins 
University. 1892. 8vo.; p. 41. A ; 
||Erwin F, Smith: “ The Bacterial Diseases of Plants: A Critical Review,” &c., I 
American Naturalist, Vol. XXX., p. 632, 1896 
