•VIay 3, 1917] 



NATURE 



195 



inadequate and is rapidly diminisliing. The supply of 

 teachers in grant-earning- schools is at present largely 

 derived from the pupils passing from the primary 

 schools to the secondary schools, there to be maintained 

 out of public funds almost entirely throughout their 

 scholastic career. Education authorities, in their en- 

 deavours to obtain the necessar)' staffs, have adopted 

 tlK- doubtful policy of attracting pupils to the pro- 

 fession by the offer of educational facilities and in- 

 creased maintenance allowances, in some cases despite 

 the moderate standard of ability displayed. 



However anxious the Government may be to em- 

 bark on far-reaching schemes, it will fail unless the 

 supply of the men who are to carry out those schemes 

 is present ; and the supply of men of the right' type 

 will not be forthcoming- unless (i) a national minimum 

 salary scale of really adequate terms is established 

 for all teachers in secondary schools ; (2) teachers are 

 free to move from one area to another without loss 

 of position, salary, and pension rights. 



Such a-system would do away, once for all, with the 

 present enormous disparity in the salaries of different 

 men with the same qualifications engaged in the 

 -ame work and in similar areas. 



The present time affords an excellent opportunity 

 introducing a system obviously necessary and long 

 'jverdue. It is to be hoped that the Government will 

 not adopt the futile policy of trying to patch up here 

 and there, but will lay the foundation of a national 

 structure in which every child shall enjoy, as a birth- 

 right, the most suitable and valuable education com- 

 patible with its- capability. 



g. d. dunkerlev. 

 Alex. Blades. 



SOIL AERATION IN AGRICULTURE. 



COME time ago (Nature, Februan,- 24, 1916, vol. 

 •^ xcvi., p. 716) v\'e directed attention to a paper 

 by Mr. and Mrs. Howard, of the Agricultural Research 

 Institute, Pusa, on the ventilation of Indian soils. 

 " More air and less water " was then set before the 

 native cultivator as the secret of successful crop pro- 

 duction. With characteristic enthusiasm for his sub- 

 ject, Mr. Howard has since developed this idea in a 

 lecture given during a meeting of the Board of Agri- 

 culture at Pusa, and now published as Bulletin No. 61 

 of the Agricultural Research Institute. Although dis- 

 cussed chiefly in relation to Indian conditions, and 

 particularly the alluvial soils of the Indus and Ganges 

 valleys, the subject in its broader aspect is of universal 

 importance to agriculture. The heavy rains of the 

 monsoon falling on these soils, which' consist largely 

 of small particles of fairly uniform size, cause the 

 surface to run tc^ther and form a crust; the soil 

 loses its porosity and aeration is impeded. The remedv 

 advocated is the incorporation with the first foot of 

 soil of thikra (tile fragments) at the rate of 50 tons 

 per acre. Leguminous plants like gram respond at 

 once to the improved aeration. Nothing is said as to 

 the cost of this treatment, orif it can be applied cem- 

 mercially over considerable areas. 



Java indigo is another leguminous plant of special 

 interest, and about this Mr. Howard has a great deal 

 to say in relation to soil aeration. He holds that the 

 variable dyeing power which has greativ handicapped 

 the natural indigo in competition with' the svnthetic 

 product of the German factories is due to defective 

 and irregular aeration. The indigo plantations of 

 Bihar lie on the higher ground of an undulating 

 country with rice i- the valleys between. During the 

 monsoon all the countrv becomes more or less water- 

 '■^gged except the crest of the ridges, and occasionally 

 NO. 2479, VOL. 99I 



some of these go under. The high-water mark is said 

 to be rising at the rate of 3 in. a year, owing to in- 

 creasing interference by embankments (canal,, rail, afid 

 road) with the natural drainage of the countr}'. Mr. 

 Howard suggests that " when a railway has to run 

 across a broad, shallow drainage line, it might pay to 

 lay it flat and to let the water run over it. -At most 

 the interruptipn of traffic would not be a very long 

 one." It would be interesting to hear What the per- 

 manent-way departments and traffic superintendents 

 of the Indian railways think of this idea. Whatever 

 the cure, it is evident that the activities of the civil 

 engineer have been harmful to agriculture in some 

 ways, and a good case is made out for a thorough 

 study of the drainage systems of India from this point 

 of view. 



W'ith regard to water supply, the author goes even 

 further than in his previous paper, and suggests that 

 some of the money now wasted on over-irrigation 

 might more profitably be spent on aerating stations for 

 the supply of oxygen to the insufficiently aerated water 

 of the rice swamps. In this connection a sharp dis- 

 tinction is drawn between rice and other plants which 

 is difficult to follow. It is said that while the former 

 takes up its oxygen in the dissolved state from the 

 swamp water, other plants, e.g. wheat, assimilate it 

 as free oxygen. As the root-hairs of the wheat plant 

 must be in contact with moisture if they are to function 

 properly, it is probable that oxygen, like other plant 

 foods, passes in solution through a film of water sur» 

 rounding the roots. Wheat, barley, and peas all grow 

 well in water culture so long as the nutrient solution 

 is kept aerated. If the supply of dissolved oxygen 

 falls off, the plant suffers at once, even if the upper 

 roots haye access to free oxygen. The distinction 

 between swamp rice and wheat seems rather to be that 

 the former requires much water and relatively little 

 oxygen, while the latter needs a moderate amount of 

 rnoisture and much oxygen. Under favourable condi- 

 tions wheat obtains this by the rapid passage of the 

 gas through the water films surrounding the roots and 

 soil particles. 



Turning homewards, the variation in the quality 

 of malting barlevs grown on different British soils 

 is shown to be due to soil aeration. The best malt 

 comes from the light land where natural aeration is 

 good. One effect of the exj>ensive organic manure 

 used by market-gardeners and hop-growers is to in- 

 crease the aeration of the soil and encourage root 

 development. It is suggested that a permanent aerator 

 like the Indian thikra might achieve the same result 

 at a lessened annual charge for manure. 



We have only touched on a few of the manv in- 

 teresting points raised in Mr. Howard's lecture, which 

 deals with one of the most important factors in crop 

 production. Although the necessity for soil aeration 

 has been unconsciously recognised ever since man first 

 drove a spade into the earth, because of its ver>' 

 obviousness agricultural science has scarceLv ^iven 

 the subject the attention it deserves. E. H. 1?. 



THE INDIAN ASSOCIATION FOR THE 

 CULTIVATION OF SCIENCE.^ 

 nPHE genetic relation between the serious pursuit of 

 ^ natural science and the profession of medicine 

 is nowhere better illustrated than in British India, and 

 in British India nowhere better than bv the Asiatic 

 Society pf Bengal (the original "Asiatick Society"), 

 and by its autochthonous coneener, the Indian .Asso- 

 ciation for the Cultivation of Science, founded in 1876 



1 Report of the Indian .^^ociation for tl e Culti^atioD of Science for the 

 :(, alcutta. 1910. 1 



