Vol. III. No. 58. 



THE AGEICULTUKAL NEWS. 



215 



SCIENCE NOTES. 



Galba. 



This useful fore.sttree, known botanically as CalojAyllum 

 Calaha, is a native of the West Indies and tropical 

 America. Altliough of considerable importance as a timber 

 tree, its wood being much used for building [lurposes 

 and for making furniture, it is more particularly to be 

 recommended for planting as a wind-break. It is a lofty 

 tree, .sometimes attaining a height of over 100 feet, with 

 a straight trunk and dense top. Its seeds contain an oil 

 which is exjiressed and used for burning. As this is 

 about the time for galba to form its fruit, we would urge 

 planters to save its seeds for planting. Large numbers of 

 seeds are being sown at some of the Botanic Stations, but it 

 is impossible to raise, in these limited areas, as many 

 seedlings as it is desirable should be planted out. 



It is lioped that the efforts of the Department to 

 encourage the planting of wind-breaks in exposed situations 

 will receive the practical sujiport of planters. 



Leaf Structure and Environment. 



A recent issue of the Journal of the Linnean Society 

 contains an interesting paper by Jlr. L. A. Boodle, F.L.S., on 

 'The Structure of the leaves of the Bracken {Pteris aquilina, 

 Linn.) in relation to Environment.' 



The bracken, as the author points out, is a fern which 

 grows in very diverse habitats, for instance, on dry heath 

 land, and also in damp and shaded woods. It has long been 

 known that the external features of the plant vary according 

 to its habitat ; deep shade and shelter from wind bring 

 about a more foliose and spreading habit, while exjiosure 

 tends to a harder and dwarf habit ; there are also differences 

 in leaf-colour, hairiness, etc.. 



On examining the structure of leaves from different 

 situations, Mr. Boodle found striking anatomical diflferences, 

 which he gives as follows : — 



' In the exposed leaf, as compared with the sheltered 

 one, the outer wall of the upper ejiidermis is considerably 

 thicker, there is a well-differentiated hypoderm, the thickness 

 of the leaf is considerably greater, the palisade tissue usually 

 occupies a distinctly greater [iroportion of the niesophyll, and 

 its cells are more elongated, while the spongy tissue usually 

 appears less lacunar. In the sheltered leaf there is practically 

 no hj'poderm, while a certain number of epidermal tells may 

 contain chlorophyll ; there may also be uo differenfiafed 

 palisade.' 



As the author points out, the presence of a distinct 

 hypoderm (a layer of colourless cells immediately below the 

 upper epidermis) in some cases and iiractically none in others 

 is an example of a wide range of structure. 



One case in which diflerent parts of the same leaf showed 

 these different characters is of great interest : a leaf about 

 6 feet high had grown ui» through a dense bush. The 

 lower jiart of this leaf showed the structure of a sheltered 

 leaf as described; the uppermost leaflets had overtopped the 

 bush, and these showed all the characters of an exposed leaf. 

 This proves that the mature structure of the leaf is not 

 determined up to a very late stage of its growth. 



The author also discusses the different factors which 

 may determine the leaf-structure and comes to the conclusion 

 that light is not the 'all-important character deternuning 

 the structure of sun leaves and shade leaves.' Dryness of 

 air, exposure to wind, dryne.ss or coldness of .soil usually 

 accompany strong light in exposed situations, and any one of 

 these may be a determining factor, at least in part. 



The Purification of Water Supplies. 



It frequently happens that small ponds and other 

 reservoirs of water become filled up and spoiled by the 

 growth of a green slime caused by the development of 

 a variety of algae. This slime often gives to the water 

 a distinctly objectionable taste and odour. So important 

 was this matter considered in the United States that special 

 investigation was made, by Mersrs. Moore and Kellerman, of 

 the Bureau of Plant Industry (U.S. Department of Agri- 

 culture), into methods of destroying the growtli. Their 

 results have been published in Bulletin No. 6i of the Bureau. 



It was found that a very dilute solution of blue-stone 

 (copper sulphate) was sufficiently toxic to destroy the algae 

 or to prevent their appearance. The solution was so dilute 

 as to lie colourless, tasteless, and harmless to man. 



The method of applying the copper suliihate is to put 

 the required amount of the salt into a coarse bag, attach 

 this to the stern of a row boat, near the surface of the water, 

 and then row slowly backwards and forwards over the water. 



The method can be ajjplied to all kind of reservoirs, 

 pleasure ponds, water cress beds, etc. 



It is suggested that co}iper sulphate can be used in this 

 way to destroy mosquito larvae and also to destroy the germs 

 of cholera and typhoid in drinking water. 



RICE CULTIVATION IN BRITISH GUIANA. 



The following- notes on experiments witli different 

 varieties of rice at the Botanic Gardens, is taken from 

 the Demerara Daily Chronicle of June 15: — 



A considerable area of land which has been reclaimed 

 from bush at the north-east corner of the Gardens is planted 

 with rice, and the soil has turned out more satisfactory than 

 was at first anticipated. This land was planted with some 

 fourteen varieties of rice, presented by the Government 

 Secretary (the Hon. A. M. Ashmore, C.M.G.), 20 square 

 roods being allotted to each variety. A preliminary crop 

 was taken off but not tested. The second crop is now grow- 

 ing, and promises remarkably well. With irrigation almost as 

 perfect as could be desired and all other conditions favourable, 

 the cultivation presents a model which the farmers would do 

 well to imitate. It is interesting to note that at the Gardens 

 the Creole rice is nuich behindhand as compared with the 

 introduced varieties and, moreover, takes considerably longer 

 to mature. 



In other parts of the experimental fields the rice cultiva- 

 tion is being extended. Since last year, the whole acreage of 

 the fields has been enclosed with a new barbed wire fence, which 

 has been set back so as to include within its boundary the 

 trenches which were outside the old fence. These trenches will 

 in all probability be utilized for rice growing in the same way 

 as that running pai-allel to the vinery has been. Here what 

 is known as hill rice has been most successfully grown and 

 reaped just four months after planting. Experts say that 

 they have seldom, if ever, seen hill rice give such an excellent 

 yield, in such circumstances, the particular variety not 

 usually being cultivated under the conditions which prevail 

 there. The seed will probably be distributed between 

 various Government institutions in other parts of the colony 

 with the object of further testing its .suitability under varying 

 conditions for cultivation here. 



In every sense the experiments with rice may be 

 deemed highly satisfactory, and every facility will be afforded 

 the rice cultivators throughout the colony to obtain seed of 

 the new varieties which have shown themselves superior 

 in growth to the Creole rice. 



