Nov. 5, 1874] 



NATURE 



meableby it. A clayey soil offers, as observation proves 

 no less than reason, great facilities to the passage of the 

 insect, which is not hindered by its slippery nature when 

 wet, for it can walk without difficulty up the vertical sides 

 of a glass bottle. Such a soil cracks everywhere in 

 drying, and forms fissures in all directions, vertical 

 and horizontal, thus laying bare the roots of the vines 

 in many places; moreover, the digging and dressing 

 of the vine leaves the soil in lumps about the roots, sepa- 

 rated by numerous chinks which afford every facility to 

 the passage of the insect. A calcareous soil generally 

 resembles a clayey one with respect to the means it 

 affords for the movements of the Phylloxera ; it is only 

 when the limestone it contains is disseminated through it 

 in the shape of sand or small gravel that a calcareous soil 

 at all resembles in its properties a sandy formation. This 

 latter kind it is, which, being always dry, always well 

 settled, constantly enveloping the roots on all sides, puts 

 great obstacles in the way of the circulation of the insect, 

 which can find no chinks large enough for its purposes 

 underground, while on the surface it gets entangled in its 

 movements like a fly in a dish of honey. A soil formed 

 of large pebbles cemented together with clay will not, how- 

 ever, be favourable to the Phylloxera, for it does not crack 

 like the purely argillaceous formation ; and though the 

 vine, which can push its way everywhere, does so there also, 

 the insect cannot. A very little clay more or less serves 

 to give very different properties to the earth from the point 

 of view of the Phylloxera, and hence it is that one can 

 explain a phenomenon often noticed, namely, a small 

 portion of a vineyard rema-ning in a flourishing condition 

 in the midst of general decay. A close examination of 

 the soil in these cases removes all cause for wonder, for a 

 lump of damp earth taken from the diseased quarter and 

 pressed between the fingers may be worked and moulded 

 like dough, while a piece taken from the healthy part 

 crumbles and is less tenacious. Were it otherwise at all 

 doubtful, figures would show that the vines in the south- 

 east of France are healthier or the reverse, according as 

 the soil is less or more clayey. Thus a physical analysis 

 of some earth taken from a vineyard of iVI. Faucon, at 

 Graveson, where all but one little plot was subjected to 

 the attacks of the Phylloxera, gives the following re- 

 sults :— 



Healthy part. Diseased part. 



Water ' 2-25 ... 3-20 



Nitrogen on ... 012 



Sulphate of calcium , o'62 ... 0-42 



Chloride of sodium 1'I5 •■■ o^\% 



Carbonate of calcium 49'oo ... 42^00 



Siliceous sand 23-50 ... io-20 



Clay 1775 •■■ 3y5o 



Organic substances and errors ) .g, g.,g 



of analysis \ 



Among the different varieties of soil which are more or 

 less favourable to it, the Phylloxera as one would suppose 

 without observation shows traces of its presence in a 

 poor dry and shallow soil first of all, then in clayey 

 damp ground, and after that in calcareous tracts, according 

 to the degree of difficulty which vines, planted in these 

 soils, present to its operations ; eventually, in the same 

 way, the disease shows itself in other kinds of earth, with 

 a rapidity or the reverse which is in proportion to the 

 amount of strengthening juices which the vine can imbibe 

 from them, and the obstacles which the insect meets with, 

 till at last no vines are left intact but those which are 

 planted on a soil impenetrable to the parasite. This 

 phenomenon, if such it may be called, of the disease, will 

 serve to explain, what we have already discussed in a 

 former article (vol. x. p. 503), the spread of the disease 

 in its earlier years, and the great and alarming in- 

 crease of the extent of territory affected in 1867-1 868. 

 Regarding the observations just made, we can see that 



probably the Phylloxera was spread over the whole 

 area of the two departments of Vaucluse and Bouches- 

 du-Rhone, which in the two last-mentioned years 

 were so formidably damaged in their vineyards, as 

 early as 1S65, when the disease only appeared on the 

 plateau of Pujaut. The alternative hypothesis, that the 

 disease radiated from a central point at Pujaut, presents 

 great difficulties, as it does not allow sufficient time for 

 the emigration of the insect to the points where it ap- 

 peared in 1S67-1868, while it makes it leave a district 

 not in any way exhausted, disregarding the known habits 

 of the Phylloxera. It would seem, therefore, that we may 

 put aside any idea of a progressive irradiation of the 

 disease around a single centre, and explain existing facts 

 by attributing them to a general dissemination of Phyl- 

 loxera, before 1866, over the territory lying along the 

 valley of the Rhone, between the Drome and the sea, 

 though the insect only showed traces of its presence 

 according to the nature of the soil in different parts, in 

 some sooner, in others later. We may, indeed, regard 

 it as almost certain that the disease began with the 

 invasion before 1865 of a vast surface, in which different 

 points have shown the traces of the insect's presence suc- 

 cessively, and that from a cause analogous to that which 

 shows us, when an island emerges from the se-i, its 

 highest peaks appearing first, the others afterwards, in 

 the order of their altitude. By the use of this illustration, 

 supplied by M. Duclaux, we can set before ourselves a 

 graphic picture of the history of 1S65, 1S66, 1867, and 

 1868 in the vineyards of South-eastern France. 



We will not dwell at any length on the different 

 attempts at treatment of the disease, as they have more 

 practical interest for those who live in vine-growing 

 countries. Many of these attempts have been failures, 

 owing to their having been based on false hypotheses as 

 to the origin of the disease of the vine. When, in July 

 1 868, M. Planchon discovered the Phylloxera, attention 

 was naturally turned to the employment of insecticides, 

 but the difficulty lies, not in the discovery of a substance 

 fatal to the insects and harmless to the vine, but in its 

 application underground to all the parts attacked. It was 

 soon found that those insecticides, at least, which are 

 insoluble in water, cannot be applied generally to the seat 

 of the disease, and this fact led to the trial of immersion, 

 in the hope that, instead of being like many remedies 

 suggested, only partial, serving merely to delay the death 

 of the vine, it would prove a radical means of cure. M. 

 Faucon was the first practical vine-grower to employ 

 immersion, as distinguished from the mere watering of 

 the vine ; but this method, though entirely successful in 

 his case in the parts where it was applied, is obviously 

 not capable of universal adoption. The physical con- 

 fomration of the soil, the absence of a water-supply from 

 any river, and the fact that the finest vines grow on 

 slopes, which are not of course amenable to this treat- 

 ment, to which we may add its great expense, except in 

 very conveniently situated districts, make it only practi- 

 cable over limited areas. The remedy, therefore, which 

 is to eradicate the Phyllo.xera and restore to France her 

 full supply of wine, the national drink and the great 

 source of national material prosperity, is still undis- 

 covered. Science throughout France is striving its 

 utmost to discover the potent method of destruction of the 

 Phylloxera, little doubting that some such there is. The 

 thought of thinking minds engaged on this subject should 

 be like that to which M. Faucon so eloquently gives 

 utterance:— "When we feel that we are threatened, and 

 see that we are already attacked, have we no other 

 resource than feverish attempts, barren lamentations, or a 

 resigned submission ? Yet help never comes but to those 

 who deserve it, and who, in wrestling with the plague by 

 which they are attacked, are obeying, whatever bigoted 

 minds may think of it, the strict call of duty— nay, we 

 may say a command of heaven itself." 



