December i6, 1909J 



NA TURE 



199 



affecting the abundance of certain species in some locali- 

 ties, and indicates the necessity for better regulation of 

 such methods of hunting. 



In a recent number of the Proceedings of the Zoological 

 Society of London (October) Dr. F. Wood-Jones gives an 

 abstract of his remarks on the new theory he has formu- 

 lated on the origin of coral reefs and atolls. According 

 to his view, the presence or absence of sedimentation 

 determines, in the first place, whether the reef corals are 

 not, or are, able to form a reef on a submerged bank. 

 The tendency of reefs, once started, to become " basin- 

 shaped " is due to the sediment that falls and settles on 

 the side of the reef that is protected by the growing corals 

 from the washing action of the sea currents. When the 

 reef reaches the tide limit the waves hammer fragment 

 against fragment and form a quantity of coral debris, 

 which becomes cemented into a solid breccia to form the 

 basis of the coral island. A small coral island once formed 

 in this manner provides an impediment to the current, and 

 the burden of sediment the current carries is deposited in 

 stream lines from its extremities. " In this way the 

 form of the island tends to becomes a crescent." The 

 theory is ingenious and full of interest, but until the full 

 paper, which we may hope will be adequately illustrated, is 

 before us, it is difficult to believe that it will entirely 

 supplant the older theories of " subsidence " or of " solu- 

 tion." Neither the simple and beautiful theory of Darwin 

 nor the more complicated but still fascinating theory of 

 Sir John Murray have received universal support; it is. 

 hardly possible that Dr. Wood-Jones's theory of sedimenta- 

 tion will prove to be capable of solving all the difliculties. 



The first appendix to the Kew Bulleiin, igio, has been 

 issued. It contains, as usual, the list of seeds of hardy 

 herbaceous plants and of trees and shrubs which have 

 ripened at Kew during the year and are available for 

 exchange with botanic gardens and regular correspondents. 



A PAPER of much interest contributed by Dr. Th. 

 \Veevers to Recueil des Travaux botaniques Neerlandais 

 (vol. vi.) discusses the physiological significance of some 

 glucosides. The author previously studied the glucoside, 

 salicin, present in twigs of Salix purpurea as a reserve 

 product, and observed that when the shoots start growing 

 it gives place to a body saligenin, and apparently this in 

 turn to catechol. He now reports the discovery of the 

 enzyme, salicase, which decomposes salicin. Further, he 

 identifies two oxidation ferments, which act upon saligenin 

 and catechol respectively. These and other results lead to 

 (he following argument. During the summer salicin is 

 formed in the leaves by day, but is decomposed by night, 

 and the glucose is transported to the cortex ; each day the 

 catechol combines with more glucose to form salicin. In 

 the autumn the process ceases, because the cortex contains 

 as much salicin as the leaves. These conclusions agree 

 with the hypothesis that benzene derivatives combine with 

 carbohydrates to form substances which diffuse with 

 difficulty, and that serve to keep the sugar stored in the 

 tissues. 



An essential feature of the scientific investigations under- 

 taken at the Rothamsted Experimental Station is the prac- 

 tical bearing of the problems involved ; this is evident in 

 the papers originally published in the Journal of Agri- 

 cultural Science (October), now issued in pamphlet form 

 from the Cambridge University Press. A communication 

 by Drs. E. J. Russell and H. B. Hutchinson deals with 

 the effects produced bv partial sterilisation of soils. When 

 a soil is heated to 95° C. or treated with volatile anti- 

 septics, e.g. carbon bisulphide, it becomes more productive 

 NO. 2094, VOL. 82] 



for a while. The authors find that there is an increase in 

 the production of ammonia, which is due to a rapid increase 

 of bacteria. Reasons are given for believing that the chief 

 factor is the destruction by sterilisation of large competing 

 organisms of the nature of protozoa. If this be so, it is 

 possible that some method may be devised for suppressing 

 these undesirable soil organisms, and the authors state that 

 this practical question is receiving attention. Drs. H. B. 

 Hutchinson and N. H. J. Miller have attacked the problem 

 of nitrogen assimilation by plants to test the evidence in 

 favour of direct absorption of ammonium salts. Experi- 

 ments were conducted with wheat and peas grown in water 

 and sand cultures under the conditions necessary for ex- 

 cluding nitrifying organisms. The results show that these 

 plants can take up their nitrogen entirely m the form of 

 ammonium sulphate, although wheat thrives better when 

 supplied with a nitrate. It is mentioned that other in- 

 vestigators have found a partiality for ammonium salts in 

 the early stages of a plant's existence, while nitrates have 

 been necessary or more fruitful in later stages. 



Solid carbon dioxide is now being used for refrigeration 

 in the treatment of certain affections of the skin. The sub- 

 stance is obtained in the form of a snow by allowing the 

 gas to escape from a cylinder in which it is compressed. 

 This snow is placed within a tube of metal or vulcanite, 

 and packed by using a solid rod which fits into the tube 

 as a rammer. In this way round or square rods of solid 

 carbon dioxide can be obtained. A rod may be held in 

 the hand with a turn or two of lint intervening, and the 

 free end may be pared to any shape by means of a knife, 

 as it is quite firm. On applying the end of a rod of this 

 kind to the skin with pressure, the frozen surface 

 immediately becomes white and hard. The process of 

 thawing occupies about the same time as the application. 

 Reaction sets in at once, the treated area becoming per- 

 ceptibly swollen in two or three minutes. A wheal forms 

 within half an hour, and often a blister is produced within 

 an hour, though with short applications this does not 

 occur. An application of thirty seconds or more is followed 

 by scarring. The application is practically painless. The 

 method is chiefly of use in the treatment of capillary naivi 

 of less than i inch diameter. The average duration of 

 the application is about forty seconds. " Port-wine mark " 

 is dealt with in this way. Some moles are amenable to 

 this treatment, and it answers well for warts. In the case 

 of warts a longer application is necessary, say one to one 

 and a half minutes, pressure being continued until a narrow 

 zone of healthy tissue is frozen around the base of the 

 wart. Keratoses (horny growths of the skin) are among 

 the diseases amenable to this method of treatment. It is 

 too early to say what will eventually be the scope and 

 liiTiits of the therapeutic utility of this agent, - but- the 

 method is of interest as an instance of another application 

 of physics to medicine. 



It is well known that in animals such as the vertebrates, 

 which have a closed vascular system, the nutrient function 

 of the blood is exercised upon the tissues through the 

 intermediation of lymph, that is, the fluid part of the 

 blood which leaks through the thin walls of the blood- 

 capillaries. The problem of lymph formation is fraught 

 with interest, and has exercised the attention of many 

 physiologists. The word leakage just employed, however, 

 implies that the main factor in its formation is the 

 mechanical one of fiUration, but this is by no means the 

 truth, or at any rate the whole truth. Osmosis is another 

 physical process concerned, and the labours of physical 

 chemists in elucidating the laws of osmosis have been 

 important from the physiological point of view ; but, in 



