Vol. XT I. No. 390. 



THE AGKICULTURAL NEWS. 



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The experiments Indicate that alfalfa and bean straw 

 •are superior to stable manure for mulching purposes. 



In the mnlchecl basins the quantity of humus as 

 measured by the intensity of the colour of the alkaline 

 extract, increased markodlj* in the first foot of soil during 

 the sniiHiitr. I 't no increase was observable at the greater 

 depth- ..ly to 120 days were required for the 



mulch .. to decompose sufficiently to produce 



ameasiii ' ' in the humus content. Alfalfa and 



manure jnu'r 1, > wiie equally etiective in producmg this 

 increase in humus. Barley cover crops produced a marked 

 increase in the humus content of the soil titty days after 

 being disked into the soil. 



The use of an organic mulch moderates the rise in soil 

 temperature during the day. The advantages of the mulch, 

 however, are not wholly attributable to this fact, nor to the 

 conservation of moisture. Wood shavings when used as 

 mulching material aflbrded as much protection in this respect 

 as alfalfa or bean straw, yet trees mulched with pine shavings 

 gave yields less than half those obtained with nmlchi^s of 

 alfalfa or bean straw. 



Surface mulching with organic material, especially when 

 available in quantities sutiioient to cover the entire surface, 

 may in the long run prove fully as effective as the use of the 

 mulching material in basins. A more immediate response 

 from the mulched basin may be expected, owing to the fact 

 that each time the basins are flooded the soluble portions nf 

 the decaying mulch are carried with the irrigation water 

 directly into the soil. In this respect the mulched basin 

 resembles a surface organic mulch in humid regions where the 

 rainfall first passes through the mulch before entering the 

 soil. Many of the citrus .soils of California contain 

 so little active organic matter that it is essential to 

 secure the advantages of the applied organic material at the 

 earliest possible date, and this appears to be brought about 

 more quickly by the use of the mulched basin than by organic 

 mulches with furrow irrigation. The mulched basin also 

 appears to be the most effective means of using a limited quan- 

 tity of mulcliicg material. 



The marked response of citrus trees in the experimental 

 tracts under the mulched-basin system justifies its serious 

 consideration by citrus growers. It is still in the experi- 

 mental stage, and its suitability to local conditions in any 

 instance should be thoroughly tested in an experimental way, 

 before installing basins on a large scale. Its final value in the 

 industry can be deteriuined only after it has been so tested 

 in comparison with other systems in commercial practice. 



An interesting paper on ascending the loftier Himalaya 

 appears in the January issue of the Geogrnpliicid Journal. 

 Ix deals principally with the ditficnlties encountered, which 

 are divided into (a) physiological difficulties, and (b) physical 

 ■difficulties. The former concern |iiincipally the question of 

 •oxygen supply. The conclusion from experimental balloon 

 ascents is that the ascent of Mount Kverest (29,141 feet) 

 without adventitious aids would be quite impossible, but 

 "from the tact that the physiological conditiou.s of mountain- 

 eers and balloonists are not comparable, the balloonists 

 'laving no opportunity of becoming acclimatized to high 

 -altitude.s, it is considered possible to make a successful 

 ascent of the hit;he>t mountain in the work! without artificial 

 -aids to respiration. 



SENILE DECAY IN PLANTS. 



The importance of arriving at a decision as to- 

 whether senile decay takes place in plants as well a* 

 in animals, lies in its relation to the effects of contin- 

 uous vegetative propagation on seed-producing plants. 

 Senile changes in the lea\es of Vitis I'ldpina and 

 other plants have been studied at f 'ornell University 

 by H. M. Benedict, and the general conclusions arrived 

 at are summarized as follows in the International 

 Revieu' of the Science and Practice of Agriculture, for 

 September 191(3: — 



The writer next draws conclusions from these observar 

 tions, and in particular envisages their application to the 

 question of the degeneration of phints reproduced by scions 

 or slips; he lays stress on the interest attaching to investi- 

 gations on this important question. Finally he examines 

 and generalizes the theories of senility, in [order to extend 

 them both to the animal and vegetable kingdom. He rejects 

 the theories relating to the localisation of senile modi- 

 fications, including the theory of Metchnikoff on the part 

 played by toxins secreted in the luain intestine of 

 animals, and in the flowers of plants. He likewise 

 does not admit that old'age is due to the accumulation 

 of katabolic products, or to the decreasing elimination from 

 the body of the products of secretion of cells placed far 

 away from the surface. To him. old age results from 

 a physical or chemical degeneration involving the 

 protoplasm itself, producing among other changes a diminu- 

 tion of permeability, and he concludes that the evidence 

 appears very strong, both from the p(jint of view of senility 

 and that of regeneration, that the duration of life is directly 

 bound up with the degree of permeability found in that part 

 of the living cell which is m contact with the surrounding 

 universe, and that in proportion as the activities of life 

 continue, the cell is entombed by an inexorable diminution 

 in the permeability of its protoplasm. The fundamental cause 

 of this diminution may very well be the colloidal nature of 

 protoplasm. The relatively sinijjle relations existing in non- 

 living complex colloidal bodies tend to be modified under the 

 action of external forces, or even by the mere action of time; 

 it -seems inevitable that the extremely complex colloidal 

 states which form protoplasm should be modified pro- 

 gres-iively by the activities of life, and by the intervention 

 of external forces. What should give rise to astonishment is 

 not the senile modifications of the protoplasm, but their 

 tardiness in appearing. 



llegeneratioii is the process by which the original arrange- 

 ment of the colloidal elements constituting the protoplasmic 

 colloids is resnred. 



Sexual reproduction is one of the methods by which this 

 regeneration is accomplished, while it is ensured by more 

 primitive methods in asexual plants 



It is for the future to solve the question whether the 

 progress of senility in sexed plants and animals can be 

 arrested or even leturded by means of regeneration such as 

 are utilized in asexual forms, and which are thus to a certain 

 extent applicable to the whole of the somatic cells The 

 knowledge which we at present possess as to the cause of 

 senile degeneration does not allow of a rash negation of tha 

 possibility of somatic regeneration. 



