374 



NA TURE 



[February 20, 1896 



another portion ; it is exhaled from the lungs, and given off in 

 still greater quantities from every burning substance. It may 

 accumulate temporarily in some regions, but the slow diffusion 

 and swifter winds carry it away. It ought to diminish as we 

 ascend above the earth's surface, but the rapidly rising and 

 falling currents of air tend to preserve a fairly uniform mixture 

 very much as they do in the case of aqueous va pour. Evidently 

 there is a general balance between the production and absorption 

 of carbonic acid gas, so that, like the temperature of the air 

 and the quantity of rain or any other meteorological element, 

 we find no great progressive secular increase or diminution. An 

 article in WoUny's Forschungen (1895, '^ol- xviii. p. 409) 

 reviews the latest additions to our knowledge of the distribution 

 of carbon dioxide in air. A comparison of the proportion of 

 the gas in samples of air obtained near the earth's surface with 

 that of samples collected by S. A. Andree at various altitudes, 

 failed to prove any diminution of carbon dioxide with altitude 

 up to the highest point, 4300 metres, obtained in the balloon 

 ascensions. On the other hand, the percentages of the gas by 

 volume throughout the different strata of air, are very much the 

 same as those observed at the surface of the earth. An apparent 

 dependence upon the wind was, however, suggested by the 

 results, and when the percentages were discussed from that point 

 of view, the general conclusion arrived at was that a descending 

 mass of air brings with it a higher percentage of carbonic acid 

 gas, which is subsequently diminished by absorption near the 

 earth's surface, so that the ascending current has a smaller per- 

 centage. The question here raised is one of great importance 

 in the theory of the interaction of the atmosphere and the 

 earth, and it can only be brought to a definite solution when the 

 greatest possible number of investigations into the percentages 

 of carbonic acid gas in the atmospheric strata arc carried out by 

 means of balloon voyages. 



Under the sensational title of " Longitudinal Light," a paper 

 by G. Jaumann appears in Wiedemann's Aniialen der Physik 

 iind Cheniie. It is based upon the law of electric discharge 

 enunciated by the same writer in 1888, according to which 

 electric waves impinging at right angles upon a kathode surface 

 favour the dissipation of the charge upon it. This was proved 

 experimentally by Hertz in the case of ultra-violet light, and by 

 Elster and Geitel in the case of ordinary light impinging upon 

 a liquid electrode in a vacumn. Wanka also proved it in the 

 case of electro-magnetic waves. Hence, so the writer argues, 

 light vibrations must have a component in the direction of pro- 

 pagation ; they must, in fact, contain longitudinal as well as 

 transverse waves. That this is so, is made extremely probable 

 by the analogy of kathode rays. The latter have the vibration 

 period of waves in wires, and are therefore pretty certainly 

 longitudinal. Now comes the question how Maxwell's electro- 

 magnetic equations, which do not admit of any but purely 

 transverse vibrations, can be made to agree with these con- 

 clusions. Jaumann gives a simple answer. Let it be admitted 

 that the specific induction capacity of a medium and its magnetic 

 permeability are affected by the oscillations themselves. These 

 " constants" will then be variable, and when introduced as such 

 into the equations, longitudinal vibrations are at once seen to 

 be possible. Each pencil of light will then be vibrating trans- 

 versely along its centre line, and towards the outer edge the 

 vibrations will become more and more longitudinal. This theory 

 is a distinct innovation ; but the author claims that it affords 

 a natural and simple explanation of a large number of discharge 

 phenomena. Thus the curious diffused reflection of kathode 

 by a plane surface is easily reduced to the fact that Huyghen's 

 principle of reflection no longer holds good. 



Although we may still identify a particular disease with a 

 particular microbe, yet there can be no doubt that the part 

 NO. 1373, VOL. 53] 



played by other microbes associated with pathogenic germs is of 

 very great importance in determining the course pursued by the 

 disease. The co-operation of bacteria is, therefore, a subject 

 which is gradually more and more occupying the attention of 

 bacteriologists, and in the last document issued by the Russian- 

 Imperial Institute of Preventive Medicine, M. Maschevsky has 

 published a very extensive series of investigations on the effect 

 upon the cholera bacillus of cultivation in the presence of other 

 microbes. Several varieties of bacteria were isolated from the 

 intestinal tract of man and animals, as well as from apples and 

 cucumbers, and with these the cholera bacillus was then grown. 

 The number of bacteria from these sources in themselves proved 

 to be harmless, but which served to exalt the virulence of the 

 cholera bacillus, appears to be very considerable. Perhaps one 

 of the most interesting results is the discovery that cholera 

 bacilli which had lost their virulence, regained it completely 

 when associated with perfectly harmless bacteria isolated from 

 apples and cucumbers. M. Maschevsky considers, therefore, 

 that he has discovered a scientific basis for the popular prejudice 

 which condemns the consumption of uncooked fruit and vege- 

 tables during epidemics of cholera. Prof. Metchnikow has 

 already dwelt at considerable length upon the effect produced by 

 the nature of the bacterial flora present in the intestine upon the 

 virulence of cholera bacilli, and seeks to explain in this manner 

 what may be described as some of the "vagaries" of cholera, 

 epidemics. The whole subject is one of great importance, but 

 one which, involving as it does experiments of the most exten- 

 sive and laborious nature, still requires an immense amount of 

 work to place on a satisfactory basis. M. Maschevsky's investi- 

 gations must be regarded as an important contribution in this 

 direction. 



Messrs. Crosby Lockwood and Son have nearly ready 

 for publication a volume entitled "Light Railways for the 

 United Kingdom, India, and the Colonies," by Mr. John 

 Charles Mackay. 



To the Hand-list of Orchids cultivated at the Royal Gardens,. 

 Kew, which has just been issued, is prefixed a preface giving an 

 interesting historical sketch of the cultivation of orchids in this 

 country. In the year 1890 as many as 766 species belonging to 

 the order flowered in the Gardens. 



The first part o, a " Geometric Descriptive," by M. A- 

 Gouilly, dealing with the geometry of points, straight lines, and 

 planes, has been published jointly by MM. Gauthier-Villars and 

 G. Masson, in the Aide-memoire Series. The second volume of 

 the work will be concerned with the sphere, cone, and cyhnder 

 of revolution, and conic sections ; while changes in planes of 

 projection and rotation will form the subject of the concluding 

 volume. 



The International Journal oi Microscopy and Natural Science,. 

 the fifth volume of which (third series) has lately been- 

 issued, contains many important contributions to the knowledge 

 of nature in the animal, vegetable, and mineral worlds. The 

 Journal is the organ of the Postal Microscopical Society, and is- 

 edited by Mr. A. Allen, with the assistance of three associate 

 editors, viz. Prof. V. A. Latham (Chicago), Mr. J. S. Brown 

 (Montreal), and Dr. F. Vicentini (Chieti). Naturalists gene- 

 rally, and workers with the microscope, will find much interest- 

 ing and serviceable information in the new volume. 



When the Austrian Government took over the administra- 

 tion of Bosnia and Herzegovina in 1879, meteorological observa- 

 tions were commenced at a few stations, the number of which 

 has now increased to seventy-seven ; three of these are of the 

 first order, or provided with complete self-recording instruments. 

 The Government of these Provinces has recently published its- 

 first volume, containing hourly observations and curves for 



