August, 1912. 



KNOWLEDGE. 



321 



charged helium atoms on oxygen of the water ? These are 

 questions which are immediately raised by this interesting 

 worlv. 



THE NATIONAL PHYSICAL LABORATORY. - 

 Volume VHI of the " Collected Researches of the National 

 Physical Laborator>' at Bushey Park " contains many 

 researches of great interest and high value. Dr. Kaye has 

 succeeded in constructing a standard metre of silica. Dr. 

 Stanton has measured the shearing stress in the flow of air 

 through pipes at speeds which cause the air to be in a 

 turbulent condition, and the frictional resistance at the surface 

 to be proportional to the square of the velocity. Dr. Rosenhain 

 and Mr. .•Xrchbutt have carried out an interesting research on 

 the alloys of aluminium and zinc which prove to be very 

 complex. Messrs. Melsom and Booth have investigated the 

 heating of electric cables, which worlc will be valuable 

 commercially. Dr. Harker and Mr. Higgins have investigated 

 the methods of taking the " flash point " of oils, and find that 

 the temperature of the oil and vapour interface is the important 

 factor. The results of work with the Fronde water tank and 

 the frictional resistance of air connected with matters dealing 

 with stability of ships and aeroplanes are advancing satisfac- 

 torily. The visibility of lights, electrical measurements, specific 

 heat of metals, and many other subjects, are included in the 

 work of the laboratory as set forth in the Report. 



ZOOLOGY. 



By Professor J. Arthur Thomson, M.A. 



STRANGE HOMES FOR EARTHWORMS.— In searching 

 for Lumbricidae on the Alps, Dr. Robert Stager followed the 

 useful plan of looking in unhkely places. In the mossy 

 cushions which often flourish on the stem and branches of the 

 sycamore (Acer psciidoplatanus) and bear ferns and various 

 flowering plants, he found four species of earthworms, — 

 Hclodrilus (Dcitdrobacna) rhcnaiii Br., H. rubidiis Sav. 

 and the variety suhnihicundits Eisen, Luinbriciis rnbcUus 

 Hoffm., and Eisciiia alpina. In cushions formed on almost 

 bare rock by plants like Dryas octopctalit. Silene acaitUs, 

 and Gypsophila rcpens, he found other earthworms. His 

 facts aftbrd interesting illustrations of the insinuation of life 

 into every vacant niche. 



TEETH OF SHREWS.— It is well-known that ordinary 

 placental mammals with various types of teeth (heterodont, 

 that is to say) never have more than three pairs of incisors. 

 Thus there is a gap between them and the old-fashioned 

 Polyprotodont Marsupials, such as the Tasmanian Wolf or 

 Thylacine, which has four upper incisors, and the Bandicoot 

 iPerainclcs), which has five. A recent study of the develop- 

 ment of the teeth in Shrews by Augusta Arnback-Christie- 

 Linde has revealed many interesting points, one of which is 

 the presence of more than three incisor germs in both jaws ot 

 Sorex araneus, and probably also in the upper jaw of Neoiiiys. 

 These extra incisor germs in the Shrew are vestigial structures 

 without any function ; they disappear without attaining full 

 development. " They are undoubtedly inherited from distant 

 ancestors, which consequently were to be found among 

 polyprotodont (and heterodont) mammals." In fact, it seems 

 as if the Shrews bridged the gap alluded to 



FAUNA OF BURROWS.— Of recent years considerable 

 attention has been paid to the various tenants of the burrows 

 made by moles and hamsters and other mammals of similar 

 habit. L. Falcoz suggests a classification of the burrow- 

 fauna into (1) " Pholeobies," which live and develop exclu- 

 sively in burrows (2) " Pholeophiles," which are often found 

 in burrows but elsewhere as well, and (3) " Pholeoxenes," 

 whose presence in burrows is accidental. He regards the 

 burrow-fauna as leading on to a cavern-fauna. In burrows of 

 mole and badger he has founcl numerous beetles and flies, not 

 including parasites belonging to the burrower and occasional 

 inmates. The Myriopods, Arachnids, and Thysanura which 

 abound in the mole's nest in winter are occasional guests, 



except perhaps the notably lucifugous species Lephthyphantes 

 aliUaciiis E. Sim, Chelifer phaleratus E. Sim, and Japyx 

 solifugiis Halid. As true members of the burrow-fauna may 

 be mentioned the Staphylinid beetles, Heterops praevia, 

 Oxypoda lon^ipcs, Alcochara spadicea, common in the 

 abode of moles, likewise the Silphid beetle Catops niarita 

 and the Dipterous fly Lycoria nervosa. 



SMELL IN FISHES.— It is probable that dilTerent fishes 

 are attracted to their food in different ways, some being 

 appealed to by the eye chiefly, others being susceptible also to 

 odours and chemical stimuU. Professor G. H. Parker, has 

 made many interesting experiments with the common 

 American Killifish {Piinditlus heteroclitus) which show that 

 in this case smell counts for much. He wrapped up pieces of 

 dogfish in cotton cloth, and the Killifishes in the aquarium 

 competed keenly for the packets. They also seized empty 

 packets, but they did not remain long about them. Other 

 experiments proved that the fish uses its olfactory apparatus 

 as an organ with which to scent its food ; i.e., " its olfactory 

 apparatus is a distance-receptor of very considerable impor- 

 tance in its daily activities." 



WEB-SPINNING PSOCHID.— Mr. E. Ernest Green calls 

 attention to a Ceylonese Psochid {Archipsochiis) which 

 produces spider-like webs on trees. While silk-spinning is 

 common among larval insects, " the power of producing silken 

 webs is extremely rare amongst adult winged insects, and 

 appears to be confined to certain species of the lower and 

 more archaic families of the order Neuroptera. The Psochid 

 in question produces silk at all stages of growth. The filament 

 is emitted from near the mouth and is carried back between 

 the legs of the insects. As they wander about they le.ave a 

 trail of silk behind them and cover whole trees with their 

 web. It looks like a snare, but it is probably protective. 

 The insects usually rest during the day on the bark beneath 

 the web, probably feeding on minute Algae and moulds. 



HABITS OF GLOWWORMS.— Mr. Elmhirst. Superin- 

 tendent of the Biological Station at Millport on the Clyde, has 

 recently made some interesting observations on glowworms 

 tLampyris noctiluca), which are often plentiful in a rather 

 marshy field adjoining the Laboratory. The males sometimes 

 appear in great swarms of at least several hundreds. The 

 females often take up and occupy a permanent position, night 

 after night, until they mate. Male glowworms, like most 

 insects, show a marked preference for red light, which is 

 curious in this particular case, since the light of the female, 

 which should be specially attractive, is at the other end of the 

 spectrum. Mr. Elmhirst also remarks that the light of Finsen 

 rays showed by Dr. Malcolm Laurie in the field did not serve 

 to attract the male glowworms. " This experiment ought 

 certainly to be tried again, and should under favourable con- 

 ditions succeed in attracting the male glowworms, since the 

 spectral analyses of Finsen rays and glowworm light are 

 similar. 



MYRMECODIA. — There has been much discussion over 

 the significance of the labyrinthine stem-tubers of Myrine- 

 codia tuberosa, a famous Javanese epiphyte. The mazy 

 passages and caverns of the tuber are tenanted by ants 

 {Iridoiiiyrmex myrmecodiac) and it seems very difficult to 

 get at the truth concerning the relations between the ants and 

 the plant. Beccari thought that the ants were responsible for 

 the labyrinth, but Forbes and Treub proved that there could be 

 typical labyrinths in the entire absence of ants. It seems 

 certain that the tuber is a water-absorbing and water-storing 

 structure. Miehe has recently pointed out that some of the 

 walls of the cavities are smooth and light brown, while others 

 are warty and dark brown. .\ dark fungus grows on the 

 rough surfaces, not on the smooth. The ants deposit their 

 excrement on the rough surfaces; they use the smooth-walled 

 chambers as nurseries. It is probable, Miehe thinks, that the 

 excrement of the ants is utilised by the plants. The ants do 

 not seem to eat anything that belongs to the plant, though 

 what they eat is unknown. Nor do we know how far the ants 

 are necessarily bound up with their convenient labyrinthine 

 shelter. 



