October 13, 1892] 



NATURE 



5?3 



toms of the Hausas subjects of careful study. All scientific 

 observations collected by these students during their residence 

 in Africa will be sent to the Association for distribution to the 

 appropriate societies. 



The Association of American Agricultural Colleges and 

 PIxperiment Stations will hold its sixth annual convention at 

 New Orleans on November 15. The different subjects assigned 

 to station workers for the Columbian Exhibition will be dis- 

 cussed. 



Prof. H. Marshall Ward, F.R.S.,ofthe Royal Engineering 

 College, Cooper's Hill, will give a course of ten lectures at 

 University College, London, on "The Morphology and Physiology 

 of Fungi and Schizomycetes." The course will begin on Thurs- 

 day, October 13, at 3 p.m., and be continued at the same time each 

 week till Christmas. 



A LARGE plant of Foiircroya is now in flower in the con- 

 servatory of the Royal Botanic Society. The secretary of the 

 Society referred to it at the meeting of the Council on Saturday 

 last. The plant is sometimes called the century plant, the idea 

 being that it flowers only once in a hundred years. In reality 

 the flower is produced only once in the life of the plant, the 

 duration or term of life varying considerably, according to the 

 treatment the plants individually receive. Specimens of the 

 Agave Americana have flowered in the Royal Botanic Society's 

 garden, the ages of them being well authenticated as over 80 

 years ; but the plant is known to flower in warmer climes before 

 twenty years of age. The present specimen of Fourcroya is 

 between twenty and thirty years old. It began on August _i 

 last to produce its flower spike, which, although the plant is slow 

 growing generally, developed at a rapid pace, so that on Sep- 

 tember 15 the tip had reached the glass roof. A square of glass 

 being removed, the flower spike continued its growth, and it is 

 now some 3 feet or 4 feet above the ridge, a total of over 30 

 feet in height. The leaves vary from 6 feet to 7 feet in length. 



In his treatise, " On the Propagation of Electric Force," 

 Prof. Hertz mentions some experiments tending to prove that 

 the production of resonance and the period of oscillation in 

 resonators are not influenced by the specific resistance or the 

 magnetic properties of the secondary conductor. But if the 

 phenomena be observed electrometrically, the individual pro- 

 perties of the metals soon show themselves. This method was 

 employed by Mr. V. Bjerknes, of the University of Christiania, 

 who gives an account of his results^in No. 9 of Wiedemann's 

 Annalen. Experiments made with copper, brass, German 

 silver, platinum, nickel, and iron show that metals have differ- 

 ent powers of absorbing the energy of electric waves. The rate 

 of absorption increases with the resistance and with magnetiza- 

 tion of the metal. Iron and nickel were able to follow the oscil- 

 lations to a certain extent, which means that their magnetiza- 

 tion was actually reversed one hundred million times per second. 



A method of exhibiting the Hertzian oscillations to a large 

 audience is described in the same number by Mr. L. Zehnder, 

 of the University of Freiburg. The two conducting rods placed 

 in the focal line of the concave mirror are connected with a 

 Geissler tube, within which the ends are placed very closely 

 together, but so that a discharge produces not a spark but a 

 general luminosity inside the tube. The secondary Hertz effects 

 are too feeble to be visible except at a very short distance and 

 in a darkened room. In this case they are augmented by a 

 kind of relay. On either side of the terminals of the resonator 

 are two other terminals from a circuit of 600 secondary cells, 

 which can be regulated so that the current is just unable to 

 traverse the distance between the terminals. As soon, however, 

 as the resonator responds to electric oscillations, the relay is 

 brought into action, and a brilliant discharge takes place. In 

 NO. 1198. VOL. 46] 



cases where such a lai^e accumulator is not available, it is pos- 

 sible to work with another inductorium, or, still better, to ob- 

 tain the oscillating current from the primary coil by bringing 

 one end of a wire into its neighbourhood, the other being led 

 to earth. By such means it is possible to exhibit the pheno- 

 mena in question without even darkening the room. 



The weather during the first part of the past week was very 

 boisterous and inclement over the whole of these islands. Be- 

 tween Thursday, the 6th inst., and Monday last, two deep 

 depressions closely following each other passed over the country 

 from off the Atlantic, and heavy gales were experienced in all 

 parts of the United Kingdom, accompanied by much rainfall, 

 while thunderstorms and hail occurred in many places. The sea 

 also was exceptionally rough, especially on our north-west coasts, 

 and caused much damage on shore. Temperature was some- 

 what low for the time of year, the daily maxima rarely reaching 

 60° in any part, while the nights were very cold. As the 

 depressions passed to the eastward the weather cleared and the 

 temperature decreased considerably, sharp frost occurring on the 

 ground over the inland parts of England. Towards the close of 

 the period the type of weather was becoming more settled in 

 character than it had been for some time past, but on Tuesday 

 a depression lay over the Bay of Biscay, which might disturb 

 our conditions. The Weekly Wealher Report of the 8th inst. 

 showed that during that week the rainfall exceeded the mean 

 in all districts except the south of Ireland, and that temper- 

 ature was from 2° to 4° below the mean, the lowest of the 

 minima ranging from 32° to 38°. The only district in. which 

 bright sunshine exceeded the mean was the Chanqel Islands ; 

 the percentage of the possible duration amounted there to 40, 

 while it was only 8 in the north of Scotland. 



The Meteorological Council have published the hourly means 

 obtained from their self-recording instruments at four observa- 

 tories for the year 1889, for periods of five days, calendar 

 months, and for the year, while means of pressure and tempera- 

 ture and totals of rainfall are also given for eveiy day. This is 

 the third year in which the observations have been published in 

 this form, instead of .the actual hourly values, as formerly, and 

 an addition has been made by including the monthly and yearly 

 mean values of the daily maximum and minimum temperatures 

 for this and the two previous years in this volume. The work 

 contains 112 quarto pages of very clearly drawn -up tables. 



Mr. H. DEVAUxhas been making interesting experiments on 

 the sense of taste in ants. Among other results he has found 

 that Lasius Jlavus, while fond of sugar, dislikes saccharine. The 

 ants swarmed around sugar laid out for them, but turned away 

 from saccharine as soon as they tasted it. Even sugar became 

 unpleasant to them when it was mixed with saccharine. It 

 seems, therefore, that sweetness is not the only quality which 

 attracts them to sugar. 



Prof. Scott has a note in the new volume of "the Transac- 

 tions and Proceedings " of the New Zealand Institute, on the 

 occurrence of cancer in fish. The fish afflicted with this disease 

 were all specimens of the American brook-trout {Salmofontina- 

 lis) kept in confinement in one of the ponds at Opoho belonging 

 to the Dunedin Acclimatisation Society. Males and females 

 were alike affected, and the diseased fish never recovered. Prof 

 Scott has been able to examine several specimens showing the 

 disease in various stages of advancement, and gives in his 

 paper a short account of the naked-eye and microscopic appear- 

 ances of the growth. The occurrence of cancer in the lower 

 animals has been frequently observed of late years, and it is by 

 no means so rare among them as it was at one time thought to 

 be. Prof. Scott does not, however, know that it has ever before 

 been noted 'n fish. 



