178 



NATURE 



[May 19, 1921 



red light is obtained by means of a filter-glass in the 

 eyepiece. To enable the observer to check the per- 

 manency of the calibration of the pyrometer, two 

 lamps are fitted which can be interchanged exactly 

 in the field by a simple transverse motion. Each 

 lamp is provided with fine adjustment in three 

 mutually perpendicular planes. The use of the pyro- 

 meter for measuring the "black body " temperature 

 of lamp filaments was demonstrated. 



Dr. E. E. Foiirnier d'Albe : Latest form of the 

 optophone. The optophone is an instrument which 

 enables totally blind people to read ordinary printed 

 books and newspapers. It is based upon the reflec- 

 tion of beams of rapidly intermittent light from the 

 type on to a selenium preparation, which produces 

 sounds in a telephone varying according to the shapes 

 of the letters. The instrument shown was kindly lent 

 by the National Institute for the Blind, London, 

 where it is in dailv use. 



Dr. Leonard Hill : Recording kata-thermometer. 

 This instrument gives a continuous record of the 

 cooling power of the environment exerted on the 

 surface of the bulb of the kata-thermometer, which 

 is automatically kept at skin-temperature. Intro- 

 duced into the bulb of the "kata," which is filled 

 with alcohol, is a coil of wire with a large tempera- 

 ture coefficient of resistance. This coil forms one 

 arm of a Wheatstone bridge, which is balanced when 

 the coil is at a temperature of 361;° C. An auto- 

 matic device is used by which the current sent 

 through the coil varies according to atmospheric 

 conditions, so that the coil is kept at 365° C. The 

 ammeter placed in series with the coil indicates the 

 variations of current, and so the cooling power. 



Sir J. J. Dobhie and Dr. J. J. Fox: Photographs 

 of absorption spectra of alkaloids. The absorption 

 spectra of the alkaloids are characteristic of the sub- 

 stance, and within certain limits may be used to 

 distinguish the class of alkaloid. The bands ob- 

 tained are the bands due to the unreduced part of 

 the molecule of the alkaloid. Thus the bands of 

 quinine, cocaine, and morphine are practically iden- 

 tical in position with those of 6-methoxyquinoline, 

 benzoic acid, and catechol respectively. Emetine, 

 cephaeline, corydaline, laudanosine, and certain other 

 alkaloids all give absorption spectra showing that 

 they contain the unreduced catechol grouping. The 

 photographs exhibited show that minute quantities of 

 the alkaloid are suflficient to obtain the characteristic 

 spectrum. Thus 03 milligram of strychnine suffices 

 to detect and characterise this substance. 



Mr. J. E. Barnard: The microscopic appearance of 

 animal tissues in ultra-violet light. Certain animal 

 tissues show marked differentiation of structure when 

 illuminated by means of ultra-violet light. The image 

 obtained is a fluorescent one, and the resulting 

 colours or tints depend on differences of chemical con- 

 stitution. Such images are often dissimilar from those 

 resulting from staining reactions. The light-filter 

 used Is glass transparent to ultra-violet radiations, 

 approximately 300-400 /j^fx wave-length, made by 

 Messrs. Chance Brothers. This Is combined with a 

 quartz cell filled with a 20 per cent, solution of copper 

 sulohate. The optical illuminating system is of quartz 

 and the sub-stage quartz condenser of the "dark- 

 ground " tvpe. Apart from the biological Interest of 

 the method, the Image so formed Is of considerable 

 value for testing the optical Qualities of microscopic 

 obiectlves, as the object so Illuminated is a perfectly 

 self-luminous one. 



The Protnzoological Laboratory. Fothamsted Ex- 

 perimental Station, Harpenden : The protozoan fauna 

 of the soil. The Rothamsted experiments have 

 demonstrated the presence In soil of an active 

 NO. 2690, VOL. 107] 



protozoan fauna, and investigations are now in hand 

 to ascertain the mofle of life of the organisms and 

 their effect on other soil inhabitants, especially bac- 

 teria. For this purpose daily counts are made of 

 bacteria and of protozoa in a natural field soil, dis- 

 criminating between active and encysted protozoa and 

 between various kinds of amoebae and of flagellates. 

 Typical forms were shown, including an interesting 

 binucleate amoeba. The daily counts were set out on 

 curves which show a remarkable periodicity in the 

 case of the flagellate Oicomonas termo, Martin, and 

 an Inverse relationship between the numbers of active 

 amoebae and of bacteria. 



Prof. Walter Garstang : Some remarkable Gastro- 

 pod larvae (Echinospira). Echinospira diaphana was 

 discovered at Messina and described in 1853 by Krohn, 

 who showed it to be the pelagic larva of Lamellaria. 

 It has two shells, one inside the other. The outer is 

 cast aside at metamorphosis. A complete series of a 

 related species from Plymouth was exhibited, where 

 the metamorphosis for the first time has been ob- 

 served. Diagrams of related species Illustrated the 

 larval evolution of the group and Its remarkable 

 parallelism to the development and evolution of 

 Ammonites. 



The Hon. H. Onslow: Abraxas grossulariata (the 

 magpie or currant moth) and its varieties, showing 

 mode of inheritance. There are many varieties of the 

 magpie moth, which are inherited according to the 

 well-known laws first formulated by Mendel. The 

 black pattern pf the type-form usually shows domin- 

 ance over the other varieties. The patterns of the 

 pale variety, lacticolor, and of the melanic variety, 

 varleyata, are combined to produce a new form, 

 exquisita. .As is well known, the lacticolor pattern is 

 linked to the female sex, and In the same way the 

 radiated varietv, actinota, is linked to the male sex. 



Dr. John Rennie: Preparations showing various 

 aspects of acarine disease in hive-bees. The specimens 

 exhibited were (i) the mite, Tarsonemiis Woodi, 

 Rennie, which is the causal organism in acarine 

 disease In the honey-bee ; (2) Infested tracheae of bees, 

 showing T. Woodi In all stages of development ; and 

 (3) tracheae showing pathological development of chitin 

 in the areas of infestation. (4) Other mites found in 

 association with hive-bees, including one other species 

 of Tarsonemus. The disease, apparently restricted to 

 the British Isles, first appeared In 1902. Affected 

 bees usually lose their power of flighty 



The Zoological Department, King's College (Uni- 

 versity of London) : Reconstruction models and draw- 

 ings made by Dr. F. J. Wyeth, Illustrating the 

 development of the auditory apparatus and adjacent 

 structures in the New Zealand Tuatara (Sphenodon). 

 The models were made of wax plates i mm. In thick- 

 ness, each plate representing an enlarged microscopic 

 section, the different systems of organs being dlstinc- 

 tivelv coloured. The drawings were for the most part 

 made from the models to Illustrate Dr. Wyeth 's 

 memoir on the development of the auditory apparatus, 

 etc., In Sphenodon, communicated to the Royal Society 

 by Prof. A. Dendy. 



Department of Zoology, British Museum (Natural 

 History) : Life-historv of the common eel (Mr. C. 

 Tate Regan). The researches of Dr. J. Schmidt have 

 shown that the common eel or fresh-water eel 

 (Anguilla vulgaris) of Europe breeds in the Atlantic 

 south-east of Bermuda. A series of larvae, Q-60 mm. 

 long, from the middle and western North Atlantic was 

 exhibited ; these growing larvae have long and slender 

 pointed teeth. The metamorphosis Into the elver, or 

 voung eel, was shown bv a photograph. Models Illus- 

 trated the changes in the adult eel when It migrates 

 to the ocean and becomes mature. 



