March 23, 1893J 



NATURE 



499 



by an Austrian botanist and geologist from whose studies much 

 new information is expected. 



One of the interesting minor results of M. Dybowski's 

 recent journey from the Mobangi to the Shari was the discovery 

 that the natives of that part of the Sudan use chloride of potas- 

 sium instead of chloride of sodium to season their food. They 

 carefully select plants which on burning yield an ash contain- 

 ing a minimum of carbonates, and extract their "salt" by 

 boiling water, subsequently filtering and evaporating the 

 solution. 



Dr. a. Gloy has recently published a very interesting dis- 

 cussion of the population of Schleswig-Holstein, tracing its 

 distribution to the character of the land. In order to represent 

 graphically the cause and effect on the same paper, the various ag- 

 glomerations of people from single cottages to towns of over 2000 

 inhabitants, are shown by dots of increasing size on a geological 

 map. It thus becomes apparent that the population is arranged 

 so that the fertile fenlands and clay ridges which run from north 

 to south are relatively thickly peopled, while the belt of sandy 

 and barren soil separating them has few houses except along its 

 boundaries. The type of dwelling in rural villages is also found 

 to vary, showing a clear relation to the former extension of the 

 Slav tribes westward before the time of« Teutonic predomin- 

 ance. 



In a careful study of the political divisions of the earth, Dr. 

 A. Oppel has come to the conclusion that about 1,700,000 square 

 miles are uninhabited or ownerless, about 5,000,000 square miles 

 more without settled government, and the remaining 45,000,000 

 square miles are occupied by definite states. He recognises 

 seventy-five such states, but most of them are of such insignificant 

 superficial extent that the eighteen largest make up 87 per cent. 

 of the whole area. 



FLIES AND DISEASE GERMS. 

 A S we become more intimately acquainted with the nature of 

 ■^ pathogenic micro-organisms, the manner in which their 

 distribution takes place al>o becomes more intelligible. For 

 several years past, through researches made by Grassi, Cattani, 

 and Tizzoni, it has been known that flies are capable of dis- 

 seminating cholera bacteria. These authors placed minute 

 quantities of these bacilli on to the bodies of flies and found 

 that after carefully preserving them under a glass shade in dif- 

 fused daylight for an hour and a half and longer, when intro- 

 duced into sterile culture media these flies gave rise to typical 

 cholera growths. These results have quite recently been con- 

 firmed by Simmonds. Further experiments on the part played 

 by flies in the propagation of disease germs have been made by 

 Celli, who fed flies with the sputum from phthisical patients, 

 also with pure cultivations of the typhoid bacillus, of anthrax, 

 and other organisms. The particular microbes experimented 

 with were afterwards demonstrated in the excreta of these flies, 

 partly by microscopic examination and partly by direct inocula- 

 tion into animals. The latter method w as especially successful 

 in the case of the anthrax and tubercle bacilli. A paper which 

 has just appeared by Sawtschenko in the Centralblatt fur 

 Bakteriologie, vol. xii, p. 893 ("Die Beziehung der Fliegen zur 

 Verbreitung der Cholera ") contains an account of some experi- 

 ments which the author has made on the fate of cholera bacilli 

 when introduced into flies. The flies used in the>e investiga- 

 tions were (i) the common small house-fly and (2) a much larger 

 variety, which, from the description given, would seem to answer 

 to our so-called •' blue-bottle fly." It was further marked by 

 its rapid flight, its rare occurrence within doors, by feeding 

 on all manner of decaying substances, besides being frequently 

 found on articles of food of all kinds. These flies were placed 

 in shallow dishes containing a few drops of broth infected with 

 cholera bacilli, after which they were removed and fed on raw 

 meat or sterile broth. In some cases the excrements of cholera 

 patients were substituted for the cholera cultures. It would 

 appear very difficult to keep flies alive in captivity, for the ! 

 healthy as well as those experimented upon died in nearly all 

 cases after twenty-four hours ; in only very few instances was it 

 possible to preserve them four days. Not only were the 

 excreta of the flies carefully examined for cholera bacilli, but in 



VO. 1221, VOL. 47] 



many cases ihe whole conlenls of the abdominal cavity were 

 removed with all the proper antiseptic precautions, and inocu- 

 lated into culture tubes. This latter practice was adopted in 

 order to satisfactorily dispose of all suggestion of the presence 

 of cholera germs in the excreta being due to their accidental 

 contamination from the feet of the flies themselves. In all cases 

 cholera bacilli were found, both in the alimentary tract and in 

 the flies' excreta. Moreover, guinea pigs inoculated with culti- 

 vations of cholera microbes obtained from the former died quite 

 as rapidly as when inoculated with ordinary cholera cultures, 

 thus showing that their virulence had not been impaired through 

 residence in the fly's body. In the intestinal tract of those flies 

 fed with cholera excreta, not only were cholera bacilli found, 

 but also other organisms lesembling the vibrio Metschnikowi 

 Gamaleia, and which on inoculation into guinea-pigs and pigeons 

 killed them in twenty-four hours. Similar results were obtained 

 when the vibrio was separated out directly from the cholera 

 excreta and inoculated into these animals. Thus in this case 

 also the virulence of the organism had undergone no abatement 

 during its sojourn in the fly's alimentary tract, thus fully con- 

 firming similar results with other organisms obtained by Celli. 

 Sometimes enormous numbers of cholera bacilli were found in 

 the alimentary tract of flies after seventy-two hours, in spite of 

 their having been fed after the first infection whh nothing but 

 sterile broth, with the object, if possible, of washing out the 

 bacilli. Sawtschenko makes the alarming suggestion that the 

 bacilli may very possibly be able, under suitable conditions of 

 temperature and nourishment, to multiply within the bodies of 

 flies, in which case the latter must not only be regarded as 

 dangerous carriers of infection, but as a hot-bed for the preser- 

 vation and further multiplication of cholera bacilli. 



SCIENTIFIC SERIALS. 



American Jotirnal of Science, March. — The specific heat of 

 liquid ammonia, by C. Ludeking and J. E. Starr. The liquid 

 ammonia used in the experiments was lound to contain 0*3 per 

 cent, of moisture, and on spontaneous evaporation to leave only 

 a trace of residue. The specific heat was measured by Kegnault's 

 method, the liquid being enclosed in a steel tube of i6'i22 cc. 

 capacity, stoppered by a steel screw. The mean value for the 

 specific heat deduced from two series of experiments was 0*8857. 

 —A .short cycle in weather, by James P. Hall. If a diagram is 

 drawn exhibiting the changes of daily mean temperature in New 

 York city for a few months it will be discovered that these 

 fluctuations occur every three or four day.«, on an average, but 

 that some have much greater amplitude than others. In the 

 course of four weeks, perhaps, there will be only two or three 

 conspicuous rises and falls. Upon further scrutiny there will 

 be observed a tendency in these more prominent features of the 

 curve to repeat themselves at intervals of about 27 days. That 

 these and kindred oscillations in New York city are, in the 

 main, representative of temperature changes over the greater 

 part of the United States becomes evident on comparing tem- 

 perature curves taken at Utah, St. Paul, St. Louis, and New 

 York respectively. A conspicuous rise of temperature at New 

 York is apt to be a day or two behind that at St. Louis, fully 

 two days behind St. Paul, and sometimes nearly a week behind 

 Utah. Mr. Hall attempts to find a relation between this 27- 

 day period and the sun's rotation, which takes place in about 

 the same time. — Kiiauea in August, 1892, by Frank S. Dodge. 

 The chief object of interest on the floor of Kiiauea was the lava 

 lake of Halema'uma'u, whose surface was found to measure 

 I2'i acres, which is much larger than any lake in recent years. 

 The lake is nearly circular in form, its longest diameter being 

 860 feet, and the shortest 800 feet. The lava was about three 

 feet below the rim on an average. Frequent breaks occurred 

 in the rim, from which large flows took place, in some cases 

 covering several acres of the floor. One large flow on the night 

 of August 25th covered about one-third of the floor, and raised 

 its level from one to four feet. The lake was at times very 

 active, with fountains playing over its surface in every direction, 

 as many as fifteen being counted at one time by a careful 

 observer. Small fountains were always to be seen in some 

 locality, and the whole surface was marked by long irregular 

 seams always in motion.— Also papers by Messrs. Chamberlin, 

 Darton, Upham, and Winslow, and the Address delivered 



