458 



NATURE 



[December 2, 1920 



probably hydrogen. The higher critical potential was 

 that at which lonisation took place. — J. Guild : The 

 location of interference fringes. The conditions under 

 which interference fringes, produced by reflection of 

 light from the two surfaces of a "thick plate," are 

 visible to an observer. The treatment lays stress on 

 the physical significance of the term " location " as 

 applied to interference fringes and on the dependence 

 of the observed phenomena on the conditions of 

 observation. For a broad source of light a formula 

 is obtained which is equivalent to that derived by 

 Michelson. For a joint source of light at infinity it 

 is shown that the fringes obtainable are equally 

 visible at all distances from the plate. — J. Gnild : 

 Fringe systems in uncompensated interferometers. 

 \n investigation of the form of the fringe system 

 observable at infinity, or in the focal plane of a tele- 

 scope, when a broad source is employed with a 

 Michelson interferometer in which the glass paths of 

 the two interfering beams are not equal. The fringes 

 may be elliptical or hyperbolic, with circles and 

 straight lines as special cases. In the recently 

 developed method of using the instrument for optical 

 testing, the fring-es due to a joint source at infinity 

 are employed. It is shown that the form of the 

 fringes in this case are unaffected bv lack of com- 

 pensation, but that the visibility of the fringes is 

 conditioned by the nature of the fringe system due 

 to a broad source. — Dr. G. Barr : A new relav for 

 heavv currents. The action of the relav depends on 

 the fact that no arc can be maintained between mer- 

 curv electrodes in hydrogen. One lead is brought to 

 mercury contained in a vertical tube within a solenoid. 

 An iron rod, at the upper end of which is a glass 

 cun floats in the mercury. The cup also contains 

 mercury, and the other lead is connected to an iron 

 rod which dips into this. When no current flows in 

 the solenoid the rim of the cup is about i cm. above 

 the level of the main body of mercury. When the 

 relay current (about o-o-* ampere) is running the iron 

 rod is sucked down until the rim of the cup is sub- 

 merged bv .qbout 01; cm. The space above the mer- 

 cury contains hydrogen. The relav can bo used to 

 break quite large currents (20 amperes) without much 

 spark. 



Edinburgh. 

 Royal Society, November i.— Prof. F. O. Bower, 

 president, in the chair. — Three connected papers bv 

 Dr. J. Rennie, Miss Elsie Harvey, and B. White : The 

 Isle of Wight bee disease. The results of these 

 investigations, which were being carried out in the 

 Parasitical Laboratory at Aberdeen, showed that the 

 so-called Isle of Wight disease was due to a small 

 mite living in the respiratory system of the bee. This 

 was contrary to the views advanced some eight years 

 ago by workers in England, who claimed that the 

 causal organism was a protozoon named Nosema 

 apis. Mr. Anderson, of Aberdeen, was the first to 

 call in question this hypothesis, and the series of 

 papers now presented established the existence of a 

 new type of parasitism in bees of a remarkable kind. 

 The small mite which was the cause of the disease 

 belonged to the genus Tarsenemus. It was highlv 

 specialised in structure, was' bred within the bee, and 

 was confined to an extremely limited, but very im- 

 portant, region of its breathing system. Within the 

 space of a few cubic millimetres scores of these 

 creatures might be seen in all stages of development, 

 sometimes packed in dense columns so as to cut off 

 effectually the air-supplv from the surrounding 

 organs. The detailed pathology described in Mr. 

 White's paper proved the destructive character of the 

 parasites' habits. Thousands of bees had been 

 examined from large numbers of stocks throughout 



NO. 2666, VOL. 106] 



the country, and it had been found that every stock 

 reported by trustworthy beekepers or certified by the 

 investigators as suffering from the disease harboured 

 this parasite. Similarly, every individual bee known 

 from its stock-history and individual symptoms to be 

 suffering from the disease was likewise found to 

 contain these parasites and to exhibit the internal dis- 

 orders which caused the disabling symptoms. The 

 investigators stated that they were now able to 

 diagnose the disease in its earliest stages while the 

 bees were capable of flying and foraging. Miss 

 Harvey's researches showed that infection appeared 

 to occur mainly in the hive, the conditions of the 

 cluster making this comparatively easy. Mites had 

 been obtained from the outside of the bee apparently 

 on their migratory passage. Tarsenemus included 

 several species destructive to plants, and there were 

 some which have been found in malignant growths 

 in man and other animals. The bee parasite was 

 more closely allied to the latter group. Many bees 

 from different countries outside Great Britain have 

 been examined, and so far Tarsenemus has not been 

 found in these. All the evidence hitherto obtaine<J 

 points to the parasite being peculiar to this country, 

 coinciding with the general testimony regarding the 

 insular character of the Isle of Wight disease. This 

 name had long been regarded as unsatisfactory, and 

 "acarine disease" was proposed as more appropriate. 

 In view of the great practical interest taken by Mr. 

 A. H. E. Wood, of Glassel, in the work of the 

 research. Dr. Rennie oroposed to designate the new 

 species Tarsenemuf Woodi. To Mr. Wood and to 

 the Development Commissioners special recognition 

 was due for having provided in equal measure funds 

 necessary to finance the investigation, and the authors 

 also record their high aopreciation of the support of 

 beekeeners throughout the country in supplying bees 

 and other assistance so essential for the successful 

 conduct of the research. — Prof. J. H. M. Wedderbnrn : 

 The equations of motion of a single particle. 



Parts. 

 Academy of Sciences, November 8. — M. Henri 

 Deslandres in the chair. — L. Lecornu : The permanent 

 movements of liquids. — P. Termier and W. Kilian : 

 The western edge of the glittering schists in the 

 Franco-Italian Alps between Haute-Maurienne and 

 Haut-Queyras. A discussion of the question as to 

 whether the contact between these schists and the 

 Briangon series is normal or abnormal. A careful 

 study of more than 100 km. shows that the contact 

 of these two strata has none of the characters of a 

 normal contact, and the idea of a stratigraphical con- 

 tinuity is highly improbable. — L. Lnmiire : The photo- 

 graphic representation of a solid in space. Photo- 

 stereo-synthesis. — H. Parenty and G. Vandamme : 

 Utilisation of the energy of tides and waves. A 

 description of an arrangement of cells made of 

 reinforced concrete, by means of which air is com- 

 pressed or rarefied by the shock of the waves. The 

 apparatus has been constructed and gives pressures of 

 2-3 kg. — j. de Lassus : A transmission of mechanical 

 energy utilising an invariable mass of gas in closed 

 circuit. — .\. Danjon : A new variable star of .short 

 period. The star d Cygnus varies in magnitude from 

 5- 16 to 5-36, and the passage from maximum to 

 minimum may be observed during one evening. — L. 

 Dunoyer : Remarks on an article by Irving Langmuir 

 and on another by R. W. Wood. A question of priority 

 — E. Jouguet : Application of the Carnot-Clausius 

 principle to waves of shock in elastic bodies. — R. 

 Biquard : .Abnormal indications furnished by radio- 

 chromometers with very penetrating X-rays. The 

 principle upon which Benoit's radio-chromometer 



