November 19, 19 14] 



NATURE 



1 1 



partial sterilisation aroused much interest among- 

 nurserymen and g-rowers who forthwith arranged 

 to have trials made in their own g-lasshouses. The 

 first efforts were, of course, crude ; methods that 

 work satisfactorily in a laboratory- with a few 

 kilos of material have a way of breaking down 

 hopelessly when it comes to handlings hundreds 

 of tons in a commercial nursery. But the second 

 season saw a g-reat improvement, and the third 

 an even greater, while perhaps the most satis- 

 factor}' result of all is that the g-rowers have col- 

 lected 2500/., half among themselves and half 

 from the Development Fund, wherewith to build 

 an experiment station to attack the special prob- 

 lems of their industry, and they have also obtained 

 for it an income of some 900/. a year for the work- 

 ing- expenses. 



stances, and finds a fundamental distinction 

 between Aolatile and non-volatile organic anti- 

 septics, illustrated in P'igs. 3 and 4. \'olatile 

 compounds partially sterilise and then disappear, 

 leaving no traces behind them : the effect on the 

 soil depends solely on the germicidal potency of 

 the substance. Xon-volatile compounds, on the 

 other hand, remain in the soil and react both on 

 the organisms and the plant, but their action on 

 the bacteria is peculiar. So long as the doses are 

 not too strong, some of the soil bacteria flourish 

 and multiply to an astonishing degree, apparently 

 feeding on the antiseptic : phenol, cresol, hydro- 

 quinone, quinone, are all among the unpromising 

 substances that produce this effect. The pheno- 

 mena are quite distinct from those observed with 

 volatile antiseptics ; the rise in bacterial numbers 



M/50 



u 



/oo 



CD 



10 



CRESOL 



OH 



a 



M/iO to h CRESOL REmiNS 



AMMONIA ANj> NITUTt 

 -PKLSENT AT END 



30 



DAYS 



60 



Fig. 4 Effect of a typical non-volatile antiseptic on bacterial numbers and production of ammonia in soils. (Buddui.) 



At present nurserymen use steam, but this 

 would not be applicable for ordinary field work. 

 The volatile antiseptics which work so well in the 

 laboratory have also proved ineffective, even if 

 the difficulties of application could be overcome. 

 Search has therefore been made among solid and 

 non-volatile liquid antiseptics. Lime was in- 

 vestigated by Dr. Hutchinson and found to 

 answer satisfactorily ; small doses are absorbed 

 by the soil, but after a certain saturation point is 

 reached the excess remains free and partially 

 sterilises. All the usual phenomena turn up to- 

 gether, and the point indicated by the chemical 

 tests is found to agree closely with that found by 

 bacteriological and plant-growth tests (Fig. 2). 

 Mr. Buddin has tried a wider range of sub- 



XO. 2351, VOL. 94] 



is much higher, but it is not sustained : there is 

 no sharp connection between the bacterial increase 

 and the death of the protozoa, and the increased 

 bacterial numbers do not produce any correspond- 

 ing increase in ammonia or nitrate. Hence these 

 non-volatile organic substances do not appear very 

 promising, and for the moment steam remains the 

 best agent : it partially sterilises ; it effects some 

 decomposition of the soil organic matter, and so 

 lightens the subsequent work of the bacteria ; and 

 it produces some substances which induce a re- 

 m.arkable development of fibrous root. Experi- 

 ments are still in hand, and we hope eventually 

 to learn sufficient about these effects to be able to 

 reproduce them in a way applicable to field con- 

 ditions. E. J. Russell. 



