YoL. V. No. 115. 



THE AGRICULTUEAL NEWS. 



301 



DEVELOPMENTS OP SCIENCE. 



The Flori'sts L\irhangi; lias the following note on 

 the influence of recent scientific developments on the 

 practice of horticulture and agriculture: — 



Seed growing has had its new birth as well as other 

 operations in the arts and sciences — a new birth noticeable to 

 every one in improved implements and tools, all great labour- 

 savers, but best illustrated by noting the development along 

 scientific lines, as for example : (1) The use by seedsmen of 

 carbon bisulphide and hydrocyanic acid gas in killing the 

 weevil in seeds ; also in killing under-surface insects and 

 grubs ; (2) in spraying garden plants to stop, on the one hand, 

 insect ravages, and, on the other hand, the extension 

 of fungous diseases; (3) the use of electric light as 

 introduced in France to force a night-time growth of vege- 

 tables cultivated in forcing houses, a growth equal to 10 per 

 cent, additional development and precocity ; (4) the practice 

 of nitroculture in connexion with plants of the Lefjuminosae 

 family, an inoculation with commercially-made cultures of 

 nitrogen-fixing bacteria, much advancing the immediate 

 development of peas and beans and laying up a store of 

 stimulating food for succeeding crops ; (5) the artificial 

 passage of electric currents by some German experimenters 

 through the length and breadth of plant beds in vegetable 

 forcing houses for the purpose of stimulating increased 

 cellular action, equal, it is said, to 10 per cent, development ; 

 (6) the use of chloroform to produce an intense rest which 

 makes it quite possible subsequently, by the application of 

 moisture and heat, to gain sixty days' advancement in the 

 blooming of flowering and fruit plants ; (7) the use of 

 electric air currents to stimulate the growth of garden and 

 field crops, a gain of 20 to 60 per cent.; (8) the electrocution 

 of insects feeding upon vines and plants both on their above 

 and underground surfaces, particularly applicable in the case 

 of grapes, roses, and fruit trees ; (9) and among the latest 

 scientific developments in connexion with agriculture is the 

 extraction and holding by mechanical and chemical means of 

 atmospiheric nitrogen, and its subsequent incorporations with 

 other things in the making of a commercial fertilizer, the air 

 offering a limitless mine, out of which to collect the most 

 important of all plant stimulants. This generalization 

 indicates that the higher practice of agriculture and 

 horticulture, of which the seed grower is the first exponent, 

 has already become one of the sciences. 



SPREAD OF FUNGUS DISEASES. 



The Journal of the Board of Agriculture for 

 August contains an interesting article upon the ' Spread 

 of Fungus Diseases by means of hibernating mycelium.' 

 It points out that, until lately, it was assumed that fungi 

 could only be reproduced by means of spores, concen- 

 trated masses of mycelium called sclerotia, or by means 

 of a mycelium that travels for considerable observed 

 distances through the soil. 



In the Agricultural News (Vol. V, p. 41) it will be 

 observed that hibernating mycelium was known to occur in 

 tubers and cuttings, used in the place of seed ; but recent 

 research has shown that seeds themselves may become 

 invaded by mycelium, which not only spreads with the 

 growing plant but also enters into its off'spring to produce 

 a race of infected plants. 



This discovery suggests that probably many sudden 

 epidemics of fungus diseases are due to the presence of this 

 Jiibernating mycelium, which spreads rapidly throughout the 



host plants, when the weather conditions are favourable for 

 its development, and unfavourable for a strong vigorous 

 growth of the host. 



Experiments have been conducted which show that 

 weather conditions are of; much more importance in the 

 appearance of epidemics of fungus diseases than was previously 

 suspected. This shows that the life-histories of the fungi which 

 cause diseases must be fully worked out before reliable 

 remedial measures can be suggested, and seems to point that 

 much success is to be looked for in the future in the raising 

 of disease-proof varieties. Such work must necessarily be 

 continuous, for parasitism in fungi is generally admitted to 

 be an acquired habit. If, therefore, it is easy to change the 

 host, the fungus may just as easily change its habit and adapt 

 itself to new conditions. 



The spread of many fungus diseases has been helped 

 along by the importation of seed from infected areas, and the 

 necessity of only importing seed from unaffected areas cannot 

 be urged too strongly. This is a subject worthy of the 

 consideration of West Indian planters, where interchange of 

 cotton seed and of cane cuttings is common, and the 

 carrying out of the recommendations of this Department, 

 with reference to the disinfection of cotton seed and the 

 treatment of cane cuttings {Agricultural News, Vol. IV, 

 p. 101, and Vol. V, p. 110) should -be continued. 



FUNCTION OF SILICA IN THE 

 NUTRITION OF CEREALS. 



A paper on the above subject, by Mr. A. D. Hall 

 and Mr. C. G. T. Morrison, was read before the Royal 

 Society on February 1, 1900. 



In the introduction it is shown that this subject received 

 the attention ot deSaussure, Liebig, Way, Sachs, and .Jodin. 

 Silica was considered an essential element in plant nutrition 

 until Sachs succeeded in maturing maize plants in water 

 cultures containing no silica, proving that silica could not be 

 placed in the same category as phosphoric acid and potash as 

 essential elements of plant nutrition. Also the stiffness of 

 cereal straw had been attributed to its presence, but this had 

 since been shown to be due to the influence of other factors. 



The question of the function of silica was therefore investi- 

 gated at the Rothamsted Experiment Station ; field experi- 

 ments were carried out in which soluble silicates were applied 

 to barley. The results indicated that the silicate gave the 

 plant such a stimulus as enabled it to develop more 

 vigorously and obtain more phosphoric acid from the soil. 



In 1904 the effect of phosphoric acid and silica upon 

 the development of the barley was carefully traced. The 

 general conclusions reached in the course of the investigations 

 are sunuiiarized as follows : — 



(1) Silica, though not an essential constituent of plant 

 food, does play a part in the nutrition of cereal plants, like 

 barley, which contain normally a considerable proportion of 

 silica in the ash. 



(2) The effect of a free supply of soluble silica manifests 

 itself in an increased and earlier formation of grain, and is 

 thus similar to the effect of phosphoric acid. 



(3) The silica acts by causing an increased assimilation 

 of phosphoric acid by the plant, to which phosphoric acid the 

 observed effects are due. There is no evidence that the silica 

 within the plant causes a more thorough utilization of the phos- 

 phoric acid that has already been assimilated, or itself promotes 

 the migration of food materials from the straw to the grain. 



(4) The seat of the action is within the plant and not 

 in the soil. 



