164 



NA TURE 



[December 14, 1905 



summer crops of potatoes, peas, &c, can be profitably 

 grown. 



Mr. T. R. Sim discussed the distribution of South African 

 ferns, and pointed out that the recent opening up of the 

 Orange River Colony, the Transvaal, and Rhodesia has 

 resulted in the filling up of many gaps in our knowledge 

 of this subject. 



Dr. Schonland gave a survej of our knowledge of South 

 African succulent' plants, chiefly from the historical and 

 systematic points of view. 



A paper \va> als ltributed by Mr. J. Medley Wood 



on the indigenous plants of Natal. 



Technical Papers. — Among these may be mentioned an 

 interesting note by Dr. Horace T. Brown, F.R.S., on the 

 dissipation of absorbed solar radiation by xerophilous 

 plants. He pointed out that in ordinary foliage leaves the 

 amount of heat necessary to vaporise the water of trans- 

 piration is so considerable that such a leaf may be sub- 

 je. ted to intense solar radiation without acquiring a 

 temperature el more than a very few degrees above that 

 of the surrounding air. In xerophilous plants, however, 

 transpiration is at a minimum, and therefore some other 

 method ol guarding against the risk of dangerously high 

 temperatures is necessary. According to the author, this 

 is to be found in the loss of heat due to thermal emission. 

 Experiments have been conducted by him (in collaboration 

 with Dr. \Y. E. Wilson) which show that a powerful cool- 

 ing effeel 1- produced b} the high thermal emissivity of a 

 leaf surface, even when transpiration is completely in 

 abeyance. 



Prof. H. H. W. Pearson communicated an interesting 

 account of his investigations into the development and 

 germination of the spores of Welwitschia. The results 

 el, (.lined show that some ol the current views of the re- 

 lationship of this extraordinary plant to the other genera 

 of the Gnetare.c must be considerably modified. 



Prof. Douglas Campbell described' the prothallium and 

 reproductive organs of Gleichenia pectinata, and directed 

 attention to the similarity that exists between them and 

 those of Osmunda. 



Prof. M. C. Potter presented two papers. In the first 

 an account was given of some experiments which showed 

 that amorphous carbon can be slowly decomposed by the 

 agency of a soil bacterium, with the evolution of carbon 

 dioxide. 



The second dealt with the healing of parenchymatous 

 tissues in plants. According to the author, the first step 

 in this process (prior to the formation of cork) is the 

 closing of the intercellular spaces by the formation of a 

 " wound-gum " similar to that described by Temme in 

 wounded xylem vessels. Thus the increased rate of gaseous 

 interchange caused by the wound is very soon checked. 



Mr. I. B. P. Evans, in a paper on infection phenomena 

 in the Uredinea?, said that it is quite possible to identify 

 different species of Puccinia by the shape of their infection 

 vesicles. 



Dr. G. Potts contributed a paper on the action of 

 calcium compounds on Plasmodiophora Brassicae (" finger 

 and toe "). Experiments show that an acid soil encourages 

 the growth of the parasite, while alkaline substances 

 inhibit it. 



A most interesting feature of the Cape Town meeting 

 was afforded by a fine collection of native plants, brought 

 together with considerable trouble by Dr. Marloth. These 

 included a number of the more striking succulents from 

 the Karroo region, and also a great many plants from the 

 south-west district of (ape Colony. The latter were, for 

 the most part, in flower, the heaths and the Iridacese in 

 particular presenting a beautiful blaze of colour. Dr. 

 Marloth also exhibited a number of ecological photographs 

 taken in various parts of Cape Colony. 



But, apart from the meetings themselves, the over-sea 

 botanists found considerable opportunities of observing the 

 vegetation of the various districts passed through during 

 the tour. It is true that much of the travelling was 

 hurried, but even when passing rapidly through a new- 

 country a botanist is able to gather valuable impressions 

 of the general facies, &c, of the vegetation. 



At the Cape, though the season was still early spring, a 

 considerable number of plants were in flower. I able 

 Mountain and the slopes of the Lion's Head were explored 



s,, far as time' permitted, and many plants characteristic 

 ol the Cape Peninsula flora were observed. Some of the 

 most striking of these were plants belonging to the families 

 Ericaceae, Proteaceae, and Restiaceae. 



Several members of Section K visited the Karroo, and 

 sp.nt some days in examining the many curious xero- 

 philous desert plants to be found there. 



In the Transvaal and elsewhere little or no rain had 

 fallen for some five months before the visit of the associ- 

 ation, and in consequence the country presented a very 

 parched and brown appearance, except where irrigation 

 had resulted in vivid patches of green crops, or groves of 

 Eucalyptus trees had been planted. The latter, as well as 

 other Australian plants, have been extensively imported, 

 and promise to become of considerable economic importance 

 in South Ahi. a 



A very striking feature of the bush vegetation in various 

 parts of the Transvaal was the extraordinary prevalence 

 ol parasitii Loranthaceas, many of the acacia and other 

 trees being loaded with the parasites. 



At Pretoria the Government experimental grounds were 

 visited, tin/ visitors being received by Mr. Smith, the 

 Director of Agriculture, and Mr. Burtt-Davy. Extensive 



piii nis are being at present carried on here with a 



view i" the introduction of new grasses to improve the 

 pasturage of the Transvaal. Other useful introduced plants 

 include several species of Atriplex (the Australian " salt- 

 hush "l. As these plants are markedly xerophilous, and 

 .11 the same time good fodder plants, they will probably 

 prove very useful in a climate such as that of the Transvaal. 

 I he agricultural department in Pretoria had also 

 arranged an exhibition illustrative of the vegetable products 

 el tin- I ransvaal. 



Mr. Burtt-Davy arranged a special botanical excursion 

 1-1 tin Magaliesberg, where the " Wonderboom, " an 

 exceedingly fine specimen of Fiats cordata, was visited. 



Other areas of botanical interest passed through included 

 the High Veld, the Bush Veld, the teak forest of Rhodesia, 

 and llie luxuriant so-called rain-forest immediately sur- 

 rounding the Victoria Falls. 



PRIZE SUBJECTS OF THE INDUSTRIAL 

 SOCIETY OF MULHOUSE. 



""THE Industrial Society of Mulhouse has issued its pro- 

 gramme of the prizes to be awarded by the society 

 during the year 1906 ; excluding the subjects which are of 

 a purely local or technical character, the following are the 

 principal prizes open to competition to all nations. 



In the section of chemistry medals of honour are offered 

 for a memoir em the theory and manufacture of alizarin- 

 red by the rapid process, for a synthesis of the colouring 

 matter ol cochineal, for a research on cochineal carmine, 

 for an investigation of the colouring matter of cotton, of 

 the transformation of cotton into oxycellulose, or of the 

 composition of aniline blacks ; also for a research on the 

 chemical changes of wool under the action of hypochlorites 

 or chlorine, for a synthesis of a natural dye, for a theory 

 of tin- manner of formation in nature of any organic sub- 

 stance, or for a chemical study of the fat of Turkey-red. 

 Several medals will also be awarded for special chemical 

 studies of mordants and their action, for the production by 

 artificial means of certain dyes, and for practical methods 

 of fixing certain dyes to the fibre. A method of manu- 

 facturing carbon tetrachloride at a price such as will 

 enable it to compete with carbon bisulphide and benzene 

 is also required. A sum of 500 francs to 1000 francs will 

 be allotted to the best compilation of the densities of 

 inorganic and organic substances in the solid state and in 

 cold saturated solution. Medals will be given for the pro- 

 duction of substances capable of taking the place of certain 

 named chemicals which have an industrial use, and for 

 the solution of a number of specified problems in the bleach- 

 ing, dyeing, and printing of textiles. 



In the section of mechanical arts a prize of 500 francs 

 with a silver medal is offered for a new method of con- 

 struiiion of building's suitable for cotton spinning, wool 

 combing, or calico printing. The following subjects will 

 receive medals: — a new type of steam boiler; an indicator 

 of the total work done in a steam engine ; new forms of 



NO. 1885, VOL. JT>~] 



