Yol. XIV. No. 



Till-: AGRICULTURAL NEWS. 



39:? 



Ducks as a Preventive of Malaria and Yellow- 

 Fever 



The usefulness and value of millions' in the de 

 tion of mosquito I 



the spr ad oi yellow fever ai in tropi 



, ntries where outbrea bese occur, a 



generallj well know n. The ( 'oi \iittt Join nai for 

 i i .i„ i 1915 refers to ducks as a ] .' e ol malaria 



and yellow fever, and gives ev;dei of their value in 

 I hi.- r pi 



'Ducks, which occur in all regions of the Globe, 

 are among the greatest enemies of mosquitoes, and 

 consequently of yellow fever and malaria. Their value 

 in this respect has been determined as follows: Bj 

 in, ans of dam two po Is of i qua] area were made in 

 ream. Ducks were placi d in one and fish in I hi 

 othi r. The former wa red of mosquitoes, 



whilst the sec I continued to maintain thi insects in 



all stages of development. Wild ducks were then 

 introduced and found to prefer the insects to all other 



i Is. A i the end of twenty-four hours no pupae were 



found in the pond, and after two days all the larvae 

 had been destroyed. These experiments confirm the 



observations of William Lockw I, who found thai 



the duck was particularly adapted to devouring the 

 the larvae on the surface of water, and of McAtee, who 

 found mosquitoes in the gizzard ofa wild duck. 



'The mosquito has numerous animal enemies, of 

 which the duck is the most widespread and 

 consequently the most suitable to cleanup unhealthy 

 marsh} districts which it would be too costl) to drain.' 



Trade of South Africa in 1914. 



In his report on the trad.' of South Africa during 

 lot ;. the < (fficer in charge for E.M. ^foade Commissioner 

 for South Africa states that trad.' up to the outbreak 

 of war was below normal. The reasons for this, in then- 

 order of increasing importance, were: drought, the 

 slump in the ostrich feather industry, and the after 

 effects ol the labour troubles in January 1!>I4. In the 

 latter part ot the year, the European war and the rebel- 

 lion in South Africa still further affected trade. The 

 total trade of the Union last year amounted to 

 £91,615,1 44,. as compared with £109,456,629 in 1913. 

 Of the 1914 total, imports of general merchandize 

 accounted lor £31,168,665 as compared with £38,408,598 

 in the preceding year. 



In regard to the exporl trade, it is mentioned that 

 the total exports of South African products declined 

 by aboul 18 percent, (i.e., from £65,114,634 in L913 

 to £53,495,076 in 1914) practically the same propor- 

 tional as in the case of import-. Exports ol 

 foodstuffs increased byover £440,000,an increase which 

 would have been greater but for the considerable 

 amount of produce used for the maintenance of troops 

 in the Union. Exports ol mineral products have 

 3U fl red from the effects of the war, although it is sat',. 

 to say that a decrease would have had to be recorded 

 even had the complications in Europe not arisen. 



A- to the futin Soutl \ can tradi 



observed that, although t here is need for caution o 

 part of business men th depressionis mainlj 



: ificial. South Afric i has a great recupi 



cannol help rising again < told is i he 

 main pioducl of the 1 60 per cent 



of it- exports; next in ot wool, 



and fluctuating vain an the 



possibilities of trade in -In- product, as there is always 

 inon or less an i a the qualities of wool 



u liii-li Soul li Aii mm can produce. ( >- 

 far less stable as a product than anj ol hers n 

 <!i alt with. And. it maj be added, the possibilities 

 of South Africa as a meal producing and 

 countrj have hardly yet been realized. 



The foregoing informal ion ha been abstracted from 

 The Board of Tradt Journalfov October 14, L915. 



A Sporting Fern. 



A very interesting question in botanical biologj 

 is that of bud variations, or 'sports' as gardeners call 

 them. For some, hitherto unexplained reasons, a plant 

 may produce from one of its leaf buds a shoot which 

 differs considerably from the rest of the present plants 

 in foliage usually, sometimes also in flower and fruit. 

 Such sports are usually carefully observed by a profes- 

 sional horticulturist: and in many cases they have 

 become the origin of improved varieties of the present. 

 plant, or of varieties valued for their striking individual 

 appearance. On the other hand, many of these bud 

 variations are not stable, that is they are unable to give 

 rise to a series of individuals perpetuating their 

 distinctive characters. In some instance.-, however, the- 

 original 'sport' gives rise to a series in which bud 

 variation seems to run riot, each individual apparently 

 being liable to throw out many different sports, some 

 of them becoming stable, and others reverting to the 

 form of their original parent. 



A striking example oi this riotous variation is 

 afforded by 'sports' first obtained from Nephrolepis 

 exaltata, a fern of world-wide tropical distribution- 

 According to an article by R. L. Benedict in the 

 Journal of the New York Botanical Garden, for 

 September 1915, asporl of this fern was first propagated 

 in a Philadelphia garden. It was afterwards speciallj 

 cultivated by a Boston garden, and still further 

 developed by Pierson in his fern house on the Hudson. 

 The result has been that the original sport has given 

 rise to more than torn well differentiated varieties. 



One- can hardly imagine thai soi f these wonderfully 



graceful varieties of 'Boston Kern', as th.y are 

 commonly called, the long drooping fronds of which 

 present the appearance ol the finesi filagree leaf work 

 could be the progeny of the somewhat stiff 

 Kephrolepis exaltata, with its simplj pinnate, or at 

 mo-t twice-pinnate fronds. The sports have not up to 

 the present iii an\ case borne an) fertile sori. Thus. 

 the multiplication of individual plants is entirely by- 

 division of the rhizom 



