440 



KNOWLI-Dni' 



NoVEMBliK, 1912. 



containing the chromophoric Kroiip and of gradually in- 

 creasing molecular weight. The continual transformation 

 of one form of a substance into another molecular 

 form of the same substance, or lautomcrism as it is 

 called, is supposed by some to give rise to the colour of 

 many organic substances. However, most of this work has 

 been of a qualitative nature ; the results have been recorded 

 on photographic plates, and it is not possible from a variety of 

 causes to judge accurately the intensity of the absorption 

 from ex.iuiiTiation of the pl.ates. Onantitative measurements 

 have lately been made by means of dillerent spectrophoto- 

 meters. In one such instrument the upper and lower halves 

 of the slit are illuminated by beams of light polarised at right 

 angles to one another, and the relation of the intensities of 



the two beams is given by the equation, /, =tan '8, where 



" is the angle through which the analysing nicol is turned. 



By means of an apparatus such as this, the extinction 

 coefficients can be found for various wavelengths of the light 

 throughout the spectrum, and the curve of absorption can be 

 accurately plotted. Houston and others have made investiga- 

 tions on the salts of many inorganic coloured substances, and 

 have tested the influence of different substances in combination 

 with the coloured metal molecules. Merton has tried the 

 difference in the absorption spectra of pure uranous and 

 uranyl salts in various solvents, and has found that solutions 

 in different solvents give quite different absorption spectra; 

 but the apparent gradual shift observed when one acid radicle 

 is replaced by another in the same solvent can be explained 

 by the superposition of the absorption curves of the two 

 compounds. It appears that the solution of a substance in a 

 solvent is attended by considerable influence of the solvent on 

 the dissolved substance, such that the molecular vibrations of 

 the latter are disturbed by the presence of the molecules of 

 the former. 



THE COUNTING OF a PARTICLES.— Professor 

 Rutherford has improved his apparatus for counting the 

 a particles from radioactive substances. The radioactive 

 material was placed in an exhausted tube behind a mica disc 

 with a hole in it. placed at the end of a testing vessel within 

 which is an electrode, which is connected to an electro- 

 meter. \ definite fraction of the a particles pass through the 

 hole and ionise the air in the vessel, which is at low pressure ; 

 this ionisation magnifies their effect enormously and a throw 

 of the electrometer needle results. The experiments have 

 been carried out lately with improved apparatus — special 

 devices for preventing the scattering of a particles on entering 

 the vessel for counting the number of throws of the electro- 

 meter needle (even one thousand per minute can now be 

 counted), each corresponding to the entrance of one a par- 

 ticle. It is now possible to detect the electrical effect of one 

 a particle when it traverses a gas at such a low pressure that 

 its range is only reduced by .20 mm. ! This is a remarkable 

 experimental achievement, when the small mass of the a par- 

 ticle (which is the same as a positively charged helium atom) 

 is considered ! 



ZOOLOGY. 



By Professor J. Arthur Thomson, M.A. 



A WHITE PORPOISE..— In Notes No. XXXIII from the 

 Gatty Marine Laboratory, St. Andrews, Professor \V. C. 

 Mcintosh reports the capture of a white porpoise in St. 

 Andrews Bay. It was a young female thirty-four inches long, 

 of a dull yellowish-white all over like a Beluga. A faint 

 longitudinal band occurred along the upper lateral region on 

 each side, and there was a somewhat crescentic dark patch 

 from in front of the eye to the angle of the mouth. The eyes 

 had the normal pigment. It may be said that this interesting 

 white form retained traces of embryonic hues. 



LONGEVITY OF BIRDS.— Anecdotal statements as to the 

 longevity of birds are as common as precise records are rare. 

 L. Petit, Senior, communicated recently to the Zoological 

 Society of France, a number of records that he was prepared 



to vouch for. We quote a few instances — a sparrow of 

 eight, a black-headed gull of ten, a blackbird of eleven, 

 a small cardinal of fourteen, and an .Amazon parrakeet of 

 twenty-five years. 



MARSUPIAL AMPHIBIANS.— In describing a new 

 species of Xototrciiia from Br.izil. L. (j. Andersson discusses 

 the origin of the dorsal pouch in which the eggs develop. In 

 the female examined there was no trace of an opening to the 

 exterior, though a large empty pouch extended as far as the 

 head. It seems likely that the opening to the pouch closes up 

 after the young have escaped. Weinland, who first described 

 the pouch of Nototrema, regarded it as due to an intucking of 

 skin, the upper leaf of the infolded skin coalescing with the 

 dorsal skin. Another view, supported by Brandes and 

 Schoenichen, that the pouch is formed from the dorsal 

 coalescence of two longitudinal lateral folds, is based on the 

 study of Nototrema pyginaeicni. In this case it is supposed 

 that the median suture opens along its whole length when the 

 young escape; that the pouch completely disappears, and that 

 it is formed anew next season. But Anders.son's new species 

 Nototrema fiilvorn/a, had a large empty closed pouch. The 

 author suggests that the pouch in Nototrema py^macum may 

 correspond to a sort of porch or vestibule to the real pouch 

 of his specimen. "The outer part of the pouch, the vesti- 

 bulum, originates from two low lateral folds, which grow 

 towards each other, and disappear again when the young ones 

 leave the pouch." 



GLACIER-FLEAS. — As a fine example of the exuberance 

 of life in a most unpropitious place, we may refer to J. Vallot's 

 account of the multitudes of " glacier- fleas " (Desoria 

 nivalis) which he observed on the nter de i}lace at Chamonix 

 between " I' Angle" and " les Monlins" (see Comptes 

 Rendus CLV, 1912, pages 184-1851. These "glacier-fleas." 

 discovered by Desor, are minute and primitive wingless 

 insects, belonging to the family of Podurids ; but they are so 

 rare that Vallot had never before seen them in his twenty-five 

 years' experience of Mont Blanc. Yet there they were 

 covering the small pools of water on the melting ice, ten of 

 them on a square centimetre I They occurred over a stretch 

 of glacier twenty metres broad by two thousand metres long, 

 and there must have been forty millions of them. This 

 illustrates the extraordinarily rapid multiplication of a very 

 rare type, and the iiuality of insurgence which is so charac- 

 teristic of life. 



SELF - EVISCERATION IN A STARFISH. — The 

 unpleasant word " self-evisceration," somewhat suggestive of 

 Hari-kari, denotes an interesting propensity or infirmity which 

 is verj' famili.ar in sea - cucumtjers or Holothuroids. Mr. 

 Nathaniel Colgan has observed a case of it in the crimson 

 starfish Cribella oculata or Hciiricia saiigiiinolenta. 

 The process began by the appearance of a small lump of 

 caeca on the upper surface and near the tip of one of the 

 arms. The extrusion went on until one pair of caeca was 

 fully exposed. It occurs "not by a catastrophic rupture, 

 but by a long-continued series of nmscular efforts, all tending 

 towards the same end." In two cases there was extrusion of 

 gonads as well as caeca. Further experiments are necessary 

 before it can be maintained that the " self-evisceration " is 

 adaptive, for the specimens were kept in unnatural conditions. 

 " I'xposed as the)' were to strong light for considerable periods 

 while barely covered with water, which from time to time 

 became more or less foul as compared with their native 

 element, the animals must necessarily have grown sickly, so 

 that the long-drawn-out muscular efforts which finally effected 

 the extrusion of the viscera may have been merely symptoms 

 of the approaching death of the organism." 



A ZOOLOGICAL PUZZLE.— In Ordovician, Silurian, and 

 Devonian strata there are curious coral-like masses, usually 

 hemispherical or cake-like, which are known as Stromato- 

 poroids. They were monographed by the late Professor 

 AUeyne Nicholson, who regarded them as Hydro^oa. There 

 has always been great doubt, however, as to their real position, 

 chiefly because of tlu' diflicully of deciphering their structure. 



