29* 



THE TROPICAL AGRICULTURIST. 



[October i, i88z. 



Certain manures are characterised by giving a rapid 

 growt,li to plants in the early part of the season. Two 

 main causes combine to render hygrosorptive manures 

 rapid in their action; they are soluble, and they have tlie 

 capacity of absorbing the moisture which renders them 

 fluid, thus distributing their particles and rendering them 

 highly available by tlie roots. 



Hyorosorption in Eelation to Fungi. 



But other incidental consequences will arise from the 

 liygrosorptive action of a manure. From certain experi- 

 ments made by Mr. Thomas Jamieson, he has discovered 

 that manures treated with sulphuric acid have a greater 

 tendency to foster the development of club-root in Turnips 

 then manures not so treated. His explanation is that the 

 fiulphur in the manure and in the Turnip is the predi.spcs- 

 ing cause of clubbing (see Report Aberdeen Agr. Assoc. 

 1880). This explanation does not seem to me to meet 

 the requirements of the case. M. Woronin has clearly 

 fihown that the cause of clubbing in the roots of Brassic- 

 aceous plants is the simple spore-bearing parasitic fungus 

 which he names Plasmodiophora brassic?e His main conclu- 

 sions have been all verified by the present writer. Now 

 the spores of this fungus, which are minute hyaline spheres, 

 lie quiescent through the winter. In the early summer, 

 if they are supplied with moisture, they give off zoospores, 

 which very soon " plasmodiate " or become fused togetlier 

 into a homogeneous, semi-liquid mass. A manure, there- 

 fore, of a hygrosorptive character, is just the very manure 

 to promote the plasmodiation of these spores, and render 

 them fit to be absorbed in the form of a fluid plasm by 

 the roots of the plants. We do not directly know that 

 Bulphur promotes the germination of this fungus, but we 

 do know that the moisture accompanying a manure dissolved 

 by sulphuric acid is a vera causa in promoting the germination 

 of tlie spores of this fungus; in other words, the applic- 

 ation of moisture to a spore prenously kept dry is directly 

 seen to cause it either to give birth to a zoospore or to 

 plasmodiate retaining its contents — both results being 

 essentially the same, and giving rise to a speck of granular 

 plasm. But upon this view any manure of a highly 

 hygrosorptive character, whether containing sulphur or not, 

 phould be fuimd promoting club-root. This, accrodingly, 

 is known to lie the case. Land manured with sea-weeds, 

 the salts forming which are highly absorptive of moisture, 

 has had to be disused as a Turnip soil — owing to the 

 prevalence of clubbing. But, indeed, all the manures here 

 tested are more or less hygrosorptive as compared with 

 Boil ; and all manures are occasionally found associated 

 with clubbing. The enormous clubbing of the Cabbage 

 roots in the market gardens around St. Petersburg, re- 

 ferred to by M. Woronin, was not caused by the use of 

 snperphosphate. And the first recorded prevalence of this 

 disease is found by that botanist in the writings of a 

 Spanish king of a date earlier than the invention of 

 dissolving manures with vitriol. Besides this fungus attacks 

 the stock Gilliflower, and other plants which never receive 

 dissolved manures. In corn-fields where no superphosphate 

 has been .-ipplied, the Charlock is in many cases found to 

 be clubbed. And the fact that clubbing in Turnips goes 

 along with superphosphate, or along with manures contain- 

 ing deliquescent salts, finds its natural explanation as a 

 corollary of the theory of hygrosorption. The manures 

 do not cause the club-root fungus any more than they 

 cause the plants in which it grows — they simply promote 

 the growth of both ; and the more rapidly the host-plant 

 grows, or multiplies its cells, the further through its tissues 

 \vill the plasm of the parasite be carried. 



The Potato manure in the above tables contains a high 

 percentage of potash, and is the most hygrosorptive of 

 the set. There can be no doubt, therefore, that the growth 

 of the non-parasitic system of the Peronospora infestans, 

 or Potato fungus, will be promoted by such hygrosorptive 

 manures. The parasitic system of this fungus, as it exists 

 in the Potato leaf, grows mostly during the night, when 

 plenty of moisture is available ; and the non-parasitic 

 mycelium, arising from conidia and resting spores within 

 the soil, can only grow and extend its lines when surrounded 

 by a moist medium. 



The manures here experimented with only began to 

 promote the germination of certain moulds after the salts 

 had been so far diluted by the water they absorbed as to 

 be harmless to the fungi; f-T it is obvious that strong 



sulphuric or other acid would be destructive to all vegetable 

 life. But if manures are favourable to the growth of 

 phsenogamous plants, all the more likely is it that they 

 will be favourable to the growth of cryptogamous plants. 

 Indeed hardly a speck of decomposing or rotting matter, 

 in other words manure, can be found free of certain parts 

 of some non-parasitic fungus. And if manures, which are 

 simply plant-food, are thus favourable to non-parasitic 

 fungi of all kinds, they must be favourable to the non-parasitic 

 elements of those fungi which attain their perfect or 

 fruit-bearing condition as parasities in the tissues of 

 phsenogamous plants. And that the hygrosorptive action 

 of manures should favour the growth of certain Cryptogams 

 is no more to be wondered at than that the same action 

 should favour the growth of certain Phaanogams. 



But these effects on fungi are rather to be regarded 

 here as incidental. The direct value of hygrosorption in 

 a manure is the supply which it draws of moisture from 

 the air for the roots of plants. The manure requires to 

 be so nearly in a liquid form, as that it may find its way 

 osmotically through the cell-walls of the roots, and it has 

 the property of being able to absorb from the air the 

 very moisture required to liquify it. The process is still 

 further accelerated by the condensation of vesicles of 

 moisture upon the young and growing fibres of the roots. 

 It is not water in the liquid form which agricultural 

 plants require, but water in the form of condensable 

 vapour, and this is what is partly supplied to them by 

 the hygrosorption of manures. 



In their ordinary market condition these manures usually 

 contain from 12 to 15 per cent of moisture. But we see 

 that they can add largely to this amount when exposed 

 to the atmosphere. And the more powerfully a manure 

 abstracts moisture from the air the more powerfully will 

 it resist drying or the giving of it up again. During the 

 night moisture will be drawn from the air, and during 

 the day a part of this moisture, vaporised within the 

 soil from the dead material of the manure, will be con- 

 densed upon the living roots and root-hairs in the form 

 of minute dewdrops to water the plants. Farmyard manure, 

 which keeps the soil open, has a mechanical value in 

 creating air-chambers, from which vapour may be condensed 

 upon the roots passing through them, succeeded by a 

 chemical value consequent upon complete decomposition. 



By what cause moisture is thus condensed upon the 

 root-hairs is doubtful. My own experimets with masses 

 of the young roots of Cress and Turnip growing through 

 little wire baskets under a water-closed glass bell, and 

 having a delicate thermometer which could be brought 

 into contact with the roots, gave no decided indication 

 that the roots were colder or warmer than the surrounding 

 air. Other trials made within the soil were not satisfactory. 

 The matter deserves further investigation, and mil probably 

 brining into view some new facts regarding the relation- 

 ship of plants and their food ; and also some new facts in 

 explanation of the theory of drainage. — Ganleners' Chronicle. 



SUBSTITUTES FOR CINCHONA BARK AND 

 OTHER PRODUCTS. 



(Pharmaceutical Societi/ Meetimj, April 1882.) 

 Mr. Holmes, Curator of the Museum, called attention 

 to various specimens on the table. He first referred to 

 some herbarium specimens of different forms of the Japanese 

 aconite plant, lent by Professor Maximowicz and gathered 

 by him in Japan. He (Mr. Holmes) had received a 

 specimen direct from Japan through Professor Kinch, as 

 being the plant which yielded the Japanese aconite of 

 commerce ; but feeling some doubt about its identity, on 

 account of its roots being more tapering than those usually 

 met with, he had sent a leaf of the plant to Professor 

 Maximowicz, asking whether he could tell if it was from 

 Aconitum Fischeri or not. He had received the following 

 letter in reply : — 



" Your aconite leaf seems to me to belong to A . Fischeri 

 itself a very polymorphous species as to its leaves and 

 size, but suflBciently different from A. A^apellus by its 

 flowers. There is much doubt yet what is to be con- 

 sidered a good species in Acomtum, the forms being ex- 

 tremely numerous, but running into each other to an 

 extent which is perfectly puzzling. But A. Fischeri can 

 be held as a species, it seems." 



