462 



NA TURE 



[March 15, 1894 



Cylindrical glass vessels about 60 cm. hi^h and 25 cm. wide 

 were employed ; from some of these the light was excluded, 

 whilst in others it was allowed free access. The temperature 

 of the latter never exceeded that of the former by more than 

 irom 2°-4°C., and in neither case did it ever extend beyond 

 from 4o''-42° C. In every instance a marked diminution in the 

 bacterial contents was observed in the insolated vessels, whilst 

 at the same time a more or less marked increase took place in 

 those protected from the sunshine ; the period of exposure 

 varied fiom one and a half to nine hours. Of particular interest 

 are the investigations made to ascertain to what depth in the 

 water the antiseptic action of the sun's rays extended. It appears 

 that when the vessels were exposed to the perpendicular as well 

 as the oblique rays of the sun, the bactericidal power of insola- 

 tion was unimpaired at the bottom of the vessel, a depth of 

 half a metre ; but when the perpendicular rays only were ad- 

 mitted, no diminution took pLice in the number of bacteria 

 present at this distance from the surface. That the oblique 

 rays rendered important service in the destruction of the micro- 

 organisms was further shown by a special bacterial examination 

 of portions of the liquid in the immediate vicinity of the sides 

 of the cylinder, for when the latter was freely exposed to sun- 

 shine, the smallest number of microbes was found in those parts 

 of the liquid which were nearest to the walls of the vessel. Dr. 

 Procacci, in summarising his results, expresses his belief that 

 the bacterial purification which takes pUce durin^ a river's 

 course may in many cases, where the rate of flow is presum- 

 ably too great to admit of sedimentation taking place, be 

 attributed directly to the destructive action of sunshine on the 

 suspended microbes. 



The Psychological Review for March contains several im- 

 portant papers, among them being one on reaction-times and 

 the velocity of the nervous impulse, by Profs. C. S. DoUey and 

 J. McKeen Cattell. The object of the authors' investigations 

 was to determine the conditions which affect the length of re- 

 action-times on dermal stimuli, and to study the application of 

 the reaction-time to the measurement of the velocity of the 

 nervous impulse in motor and sensory nerves, and in the motor 

 and sensory nerves of the spinal cord. For the application of 

 the stimuli, two points were chosen on the arm over the median 

 nerve, and two on the leg over the posterior tibial nerve. The 

 points on the arm were 30 cm. apart, and those on the leg 

 50 cm. apart, and the length of intervening nerve would be 

 nearly the same. It was found that the reaction-times were 

 longer when the stimulus was applied to the lower points on the 

 arm and leg than when the points less distant from the brain 

 were used. If the difference of time is really due to the dif- 

 ference in length of the nerve traversed, the velocity of the 

 impulse in the sensory nerve is2i"i metres and 495 metres 

 per second, respectively, for the two observers. The velocity in 

 the sensory fibres of the posteriar tibial nerves was 31 "i metres 

 per second for Prof. Dolley, and 649 metres per second for 

 Prof. Cattell. This large difference between the two observers, 

 however, is attributed to differences in the cerebral processes 

 rather than to differences in the velocity of the impulse in the 

 sensory nerve. In the case of reaction experiments with dermal 

 stimuli the electric shock was mostly used, but as the physio- 

 logical effects of the shock were found to vary greatly on dif- 

 ferent parts of the body, a method was devised for applying a 

 touch or a blow. It was found that the same objective force of 

 blow was followed by the same subjective sensation more nearly 

 than in the case of electrical stimulation. From the difference 

 in the reactions on touch when the stimulus was applied to the 

 arm and to the thigh, the velocity of the nervous impulse in the 

 sensory tracts of the spinal cord was determined as about 

 ^o metres per second. 



NO. 1272, VOL. 49] 



Messrs. R. Friedlander and Son, of Berlin, have sent 

 us a set of their " Naturse Novitates," issued during the last 

 four months. The circulars contain lists of current scientific 

 literature, the works being classified according to subjects. 



The Director of the Botanical Survey of India has published 

 two valuable additions to our knowledge of the flora of British 

 India: a report on a botanical tour in Kashmir, by Mr. J. F. 

 Duthie, and a report on a botanical tour in Sikkim, by Mr. G. 

 A. Gammie. 



We have received a fresh instalment (Band 3, 2'*= llalfte, 2''^ 

 Lieferung) of Cohn's Kryptoniamen Flora von Schlesien, which 

 includes the Tuberinei, Elaphomyceies, Saccharomycetes, and 

 the commencement of the Fyren jmycetes. Two new genera 

 and several new species are described. 



A REPORT on North- Western Manitoba, and portions of the 

 adjacent districts of Assiniboia and Saskatchewan, drawn up by 

 Mr. J. B. Tyrrell, has been published by the Geological 

 Survey of Canada. The report is accompanied by two maps, 

 one showing the geology of the region, and the other the dis- 

 tribution and character of the forests. 



In the Proceedings of the Geologists' Association (vol. xiii. 

 part 6) Mr. A. Smith Woodward briefly reviews the present 

 state of knowledge of the sharks' teeth met with in British 

 Cretaceous formations. The review is illustrated by two ad- 

 mirable plates, which will be of use to collectors ; and several 

 of the specimens described add something of importance to the 

 facts previously known. 



MM. RiCHE AND RouME Contribute to the Annales des 

 Mines (^er. 9, tome v., Liv. i, 1894) a general account of the 

 petroleum industry of the United Stales, the result of a visit to 

 the districts made by the authors in 1892. The article deals in 

 great part with the methods of refining, comparing them with 

 processes used in France ; but it also contains descriptions of 

 the production areas in the Eastern States, and gives an inter- 

 esting map of Pennsylvania showing the gas and oil districts. 



Messrs. Swan Sonnenschein and Co. will shortly publish 

 a new book by Mr. J. W. Tutt, under the title of " Woodside, 

 Burnside, Hillside and Marsh." This will consist of a series 

 of illustrated literary sketches, on somewhat similar lines to the 

 author's "Random Recollections of Woodland, Fen and 

 Hill," and will describe a series of natural history rambles in 

 various parts of Kent and the Scotch Highlands, dealing with 

 various branches of natural science in a popular way. 



The fourteenth volume of the Index-Catalogue of the Library 

 of the Surgeon-General's Office, U.S. Army, has been issued. 

 The volume comprises words between "sutures " and "univer- 

 sally." It includes 10,124 titles, representing 6426 volumes and 

 8850 pamphlets. In addition to this bulk of matter, there are 9S67 

 subject-titles of separate books and pamphlets, and 38,461 titles 

 of articles in periodicals. When the catalogue is completed, 

 jt will literally represent a solid monument to industry. 



The first of a series of monthly guides to the beauties of 

 animate nature has been published by Messrs. Bliss, Sands, and 

 Foster, under the title " The Country, Month by Month." Mr. 

 J. A. Owen and Prof. G. S. Boulger are the authors of this 

 little book, which will be followed by others, each devoted to a 

 particular month of the year. The descriptions are interesting 

 and brightly written, and dwellers in towns who read them will 

 assuredly be tempted " to put forth and brave the blast " of this 

 blustering month of March in order to see the woodlands 

 returning to life. 



We have on several occasions referred lo the interesting series 

 of reprin's being published by W. Engelmann, Leipzig. One 



