July 4, 1918] 



NATURE 



;59 



polygonal cracks by either free or chemical desicca- 

 tion. Moreover, analysis shows that septarian nodules 

 are -more aluminous towards the centre than the out- 

 side, and are therefore capable of contraction. The 

 evidence disproved the expansion theories, and showed 

 that contraction on numerous centres in a colloidal 

 medium caused the cracking, and desiccation by 

 chemical agents the contraction. The central portions 

 are not merely enclosed clay, but clay that has under- 

 gone considerable chemical modification, and the 

 original colloidal nature of the medium is so changed 

 that closing of the cracks by absorption when placed 

 in water cannot occur. Finally, the occurrence 

 of the nodules suggests their origination by rhythmic 

 precipitation according to the laws of Liesegang from 

 solutions of bicarbonates diffusing through a colloidal 

 medium. — Dr.-C. T. Prior: The composition of the 

 nickeliferous iron of the meteorites of Powder Mill 

 Creek, Lodran, and Holbrooic. A simple and Ex- 

 peditious methofl of determining the amount and 

 chemical composition of the nickeliferous iron of a 

 meteorite was describfed. The method depends upon 

 the use of dimethyl glyoxime for the separation of 

 nickel. Its application to the meteorites Powder Mill 

 Creek, Lodran, and Holbrook gave percentages respec- 

 tively of about 42, 30, and 6^ of nickeliferous iron, in 

 which the corresponding ratios of iron to nickel were 

 about 13, iii, and 5. 



Royal Meteorological Society, June 19.— Sir Napier 

 -^haw, president, in the chair.^ — Dr. S. Chapman : The 

 lunar atmospheric tide at Greenwich, 1854-1917. The 

 tidal forces due to the moon affect the aerial as well 

 as tke fluid ocean, and the lunar atmospheric tide is 

 manifested by the periodic variation in the height of 

 the barometer having two maxima and two minima 

 (high and low tide) in the course of a lunar day. This 

 variation is much smaller than the solar semi- 

 diurnal barometric variation, which is not a simple 

 solar tidal effect ; the minute lunar variation, however, 

 can be detected with ease in the records of tropical 

 observatories, where the irregular fluctuations of pres- 

 sure are small. Atteropts to determine it in the 

 records of European observatories have been made, 

 but hitherto without success. By treating hourly 

 observations of "quiet" days only, on which the baro- 

 metric range did not exceed o-i in., and by abstract- 

 ing the solar variation, the lunar atmospheric tide at 

 Greenwich' has now been ascertained. Its total ampli- 

 tude is less than 0001 in., the harmonic formula being 

 < •00036 sin (at 4- 114°) in., where i represents lunar time 

 measured, at the rate of 360° per lunar day, from the 

 epoch of upper transit. A comparison with the varia- 

 tion at Katavia (lat. 6° S.), viz. 000256 sin (2f + 65°) in., 

 suggests that the amplitude varies as the fourth power 

 of the >cosine of latitude, and that the phase also varies 

 \\ ith latitude.— Miller Christy : The audibility of the 

 gunfire on the Continent at Chignal St. James, near 

 Chelmsford, during 1017. In this paper the author 

 continues his series of observations of the sound of 

 gunfire commenced in 1915, and published by the 

 society in 19 16. Mr. Christy considers that the most 

 interesting point in connection with his observations is 

 hi- fact that there is apparently (i) a regular and 

 . •11-defined season or period during which the gun- 

 iin- is usually audible with ease, and that this is fol- 

 lowed bv (2) a longer season or period during which 

 the gunfire is seldom or never heard. The following 

 i<- the earliest and latest dates of the sound of the 

 unfire on the Continent as heard at Chignal St. 

 J.imes during the three vears 1915-17 :— 1915 : From 

 about May i to about August 31 = 17 weeks 3 days. 

 u)i6 : From about May i to about .August 15=1; weeks 

 I day. 1917 : From about April 22 to about Septem- 

 NO. 2540, VOL. lOll 



ber 6=19 weeks 4 days. — F. J. W. Whipple : Seasonal 

 variation in the audibility of gunfire. Mr. Miller 

 Christy's observations indicate that in Essex Con- 

 tinental gunfire is heard only during the summer 

 months. On the other hand, evidence collected by 

 W. Brand, and published in the Mcleorologische Zeit- 

 schrift in February, 19 17, indicates that in Germany 

 at places 100 km, or more from the firing-line such 

 sounds are heard only during the winter. Thus it 

 appears that in summer the outer zone of audibility 

 lies to the west of the source of sound, in winter to 

 the east. No theory hitherto put forward in explana- 

 tion of the existence of- the outer zone of audibility 

 is in accord with this generalisation. 



Royal Microscopical Society, June 19. — Mr. J. E. 



Barnard, president, in the chair. — Prof. Benjamin 

 Moore : Studies of activity of light in inorganic and 

 organic systems. The chief points dealt with v.'ere 

 (i) the natural modes of production of reduced organic 

 compounds with uptake of energy, (2) the synthesis 

 of formaldehyde from carbon dioxide and water by the 

 action of light, (3) condensation of formaldehyde in 

 light to form reducing substances such as sugars, 

 (4) reduction of nitrates by sunlight, accompanied by 

 energy absorption, (5) growths of organisms in nitrate 

 and nitrite-free media in presence and absence of air, 

 showing that nitrites in air are essential, and that 

 nitrogen fixation in soil is probably due to nitrite 

 fixation from the atmosphere.— Dr. E.Penard; A new- 

 type of Infusorian, Arachnidiopsis paradoxa. The 



I organism described, egg-shaped and about 1/500 in. 

 in length, has neither cilia nor setae, but its locomotive 

 organs consist of two flexible tentacula, \vhich beat 

 the water with great rapidity. The forms described 

 under the genus Arachnidium b\ Saville Kent were 

 possibly of the same type. 



Linnean Society, June 20. — Sir David Prain, presi- 

 dent, in the chair .-—Prof. H. Coutiere : Les esp^ces 

 d'Alpheidaj rapport^es de I'oc^an indien par M. J. 



I Stanley Gardiner.— Sir N. Yermolofi : A series of inter- 

 mediate forms of the Diatom genera Navicula and 

 Cymbella. An examination of the series suggests the 



I hypothesis that the large, simple, and homogeneous 



I ancestral form Navicula monmonthiatia was a primor- 

 dial species adapted to the more uniform conditions 

 of life on the planet during the pre-Glacial epochs, and 

 that the Cvmbcllae which afterwards evolved from it 

 are smaller, more complex heterogeneous forms, 

 graduallv derived from Navicula movinouthiana under 

 the influence of quite different and more varied condi- 

 tions of life and climate, which established themselves 

 on the earth after the Glacial epochs, at least under 

 the latitudes between 40° and 60° N. A similar trend 

 of changes from larger and less varied forms to smaller 

 heterogeneous ones has affected the whole of organic 

 life after the Glacial extensions towards the south. — 

 E. J. Collins: Sex-segregation in the Bryophyta. 

 Three cultures of Ftmaria hygrometrica were made in 

 Marchals's nutrient fluid as follows : — A, protonemata 

 grown from the antheridia of a male "flower"; B, 

 protonemata trrown from the perigonial leaves of the 

 same male "flower "; C, spores from a ripened cap- 

 sule. Submitted to the same cultural conditions, A 

 and B produced a sward of plants with large discoid 

 male "flowers" only, no si)orogonia being produced' 

 at anv time ; C produced j)lants bearing male and 

 female organs, resulting in a (Jonse crop of sporogonia. 

 It appears possible that vegetative development from 

 structures borne on male and female branches respec- 

 tively may, if a sex-.segregation has actually occurred 

 somatically, lead to the production of distinct male and 

 female plants. 



