Vol XI. No. 275, 



THE AGRICULTURAL NEWS. 



363 



THE INFLUENCE OF RADIOACTIVE 

 SUBSTANCES ON PLANTS. 



Work directed toward finding if radioactive substances 

 possess any influence as regards plant growth is being carried 

 out under the direction of the Professor of Botany and Plant 

 Physiology of Melbourne University. At the commencement 

 the investigations were carried out in plots; they received 

 attention on page 183 of the last volume of the Agricultural 

 News. 



A second account in the Journal of the Dejjavtment of 

 Agriculture, Victoria, for July 1912, states that the experi- 

 ments have been extended to field trials. In comparing the 

 results with those obtained in the laboratory, it must be 

 remembered that these were obtained by the use of quantities 

 of the radioactive substance impossible to employ on the 

 same scale in the field. Further caution is given that it may 

 not follow that a substance which accelerates germination 

 may be of any further advantage to the plant, and that it is 

 possible that the addition of a radioactive mineral to the soil 

 may affect injuriously the development of useful soil bacteria. 



Trials in culture fluids showed that bacteria are able to 

 develop even when large quantities of radioactive mineral 

 are present; but that there is a retarding action, increasing 

 with the length of exposure. It was proved that this influence 

 was actually due to the rays from the mineral, and not to 

 any poisonous substance dissolved from it. There were 

 indications that organisms of the Bacillus siihtilis type may 

 be more resistant to the rays of a radioactive mineral than 

 are other bacteria. 



It appears that, in the presence of bacteria, carbon dioxide 

 and water, the rays from a sufficient quantity of radio-active 

 mineral can cause the formation of small amounts of 

 formaldehyde. This substance was not present because of the 

 action of light, for the cultures were in darkness during the 

 whole of the time. It may possibly be that the retarding 

 action was caused by the formaldehyde, but the amount of 

 this does not seem sufficient to account for the whole of the 

 action. 



In the field, trials were devised to see if this retarding 

 action is shown when the mineral is employed in the 

 quantities customary when mineral manures are being given. 

 It seems that such dressings do not produce any distinct 

 action; while enormously heavy dressings actually do reduce 

 the number of soil organisms. Another result obtained was 

 that, in quantities capable of practical application, the 

 radioactive mineral does not affect appreciably the early 

 stages of germination in wheat. 



The final conclusion reached is: 'There is nothing, there- 

 fore, in these results to show that radioactive mineral is of 

 the least benefit to wheat when applied in the same manner 

 as manure, and the hopes that had been raised by the stimu- 

 lating action of large quantities upon the early stages of 

 germination, that this substance might be of use in the field, 

 have failed to be established by experiment as regards wheat, 

 at least. Whether results of value may be obtained with 

 other plants is, of course, another question, but the radio- 

 active mineral does not appear to have any direct value for 

 the growth of wheat.' 



CACAO CONSUMPTION AND PRODUCTION, 



1911. 



The Gordian has issued recently its final estimate of 

 the production (exports) and consumption of cacao for 1911. 

 This, expressed in long tons and with the figures for 1909 

 and 1910 for comparison, is as follows: — 



THE WORLD .s CACAO CROP. 



Countries. 



Gold Coast 



Ecuador 



San Thome 



Brazil 



Trinidad 



San Domingo 



Venezuela 



Grenada 



Lagos 



German Colonies 



Ceylon 



Fernando Po 



Jamaica 



Dutch East Indies 



Surinam 



Hayti 



French Colonies 



Cuba 



St. Lucia 



Congo State 



Dominica 



Colombia 



Costa Rica 



Other countries 



Total 



1909. 

 Tons. 



20,213 



31,071 



29,788 



33,290 



23,025 



14,586 



16, .585 



5.3.56 



2.240 



3,763 



3,514 



2,683 



3,166 



2,430 



1,867 



2,089 



1,351 



1,910 



546 



757 



970 



719 



231 



984 



1910. 

 Tons. 



22,751 



35.738 



36,092 



28,702 



25,821 



16,363 



16,981 



5,755 



2,931 



4,009 



4,005 



2,312 



1,716 



2,539 



2,011 



1,822 



1,.5.50 



1,390 



731 



888 



565 



292 



181 



984 



1911. 

 Tons. 



39,726 



38,883 



34,453 



34,447 



20,888 



19,518 



17,109 



5,855 



4,401 



4,3.35 



3,016 



2,953 



2,740 



2,421 



1,570 



1,462 



1,343 



1,232 



925 



670 



568 



394 



338 



1,476 



203,134 216,129 240,722 



THE WORLD S RAW CACAO CONSUMPTIOK. 



Total 



191,794 198,023 226,395 



