SCIENCE- G OS SIP. 



151 



CONDUCTED BY C. AINSWORTH MITCHELL, 

 B.A.OXON., F.I. C., P.C.S. 



j'^The Phosphorescent Thames. — Those who 

 sailed up the mouth of the Thames on any warm 

 still evening during the month of September could 

 not fail to have observed the brilliant phosphor- 

 escence of the water, continuing far above South- 

 end. The cause of this beautiful phenomenon was 

 long the subject of wild speculation, and it is only 

 within the last thirty years that its bacterial origin 

 has been recognised. Many striking instances of 

 the phosphorescence of meat and fish are met with 

 in old literature. In the early part of the eighteenth 

 century it became so prevalent in Orleans that 

 many of the butchers there were forced to destroy 

 their meat wholesale, as no one would venture to 

 buy. Curiously enough, a similar phosphorescence 

 epidemic occurred in the same town in 1870. The 

 " Transactions of the Royal Society " for 1676 con- 

 tain an account of an interesting case. In that 

 year a Dr. Beale, of Staffordshire, had his attention 

 called to a neck of veal which suddenly became 

 phosphorescent, and " shined so brightly that it 

 did put the woman into great affrightment." She 

 called her husband, and together they endeavoured 

 to extinguish the light by beating the meat, but 

 without avail ; but finally they plunged it into a 

 pail of water. The next day the neighbours were 

 invited to partake of the joint, and all esteemed it 

 as good as any they had tasted. Dr. Beale men- 

 tions as a possible explanation that the weather 

 was warm and mild ; also that the stars were 

 shining brightly. In 1800 a series of experiments 

 were made by a Dr. Hulme, from which the follow- 

 ing conclusions were drawn : (1) The phenomenon 

 was not due to putrefaction, since the luminosity 

 decreased with the advance of the decomposition. 

 (2) Spontaneous light was a constitutional principle 

 of certain bodies, and was probably the first 

 principle to escape after the death of marine 

 fishes. In 1877 Niisch detected bacteria on phos- 

 phorescent meat, and in 1879 it was proved that 

 the light emitted by phosphorescent fish was due 

 to bacterial action. Since then many species of 

 phosphorescent bacteria have been discovered and 

 described. 



Bacteria op Phosphorescence. — The different 

 bacteria which have been isolated from phos- 

 phorescent fish and sea-water vary considerably 

 in size, and in the quality and intensity of the 

 light which they emit. Thus the Bacillus argenteo- 

 pkosphorescens, which was isolated by Katz from 

 fish in the Sydney market, grows in pale-yellow 

 colonies on gelatin, and emits a silvery-white 

 phosphorescence ; whilst B. smaragdino-plios- 

 pliorescens forms greyish-white colonies, which 

 emit an emerald-green light. The light produced 

 by certain species is very rich in violet rays, so 

 much so that Fischer succeeded in photographing 

 by its own light a colony of B. pliosplwrescens- 



indicus from the water of the Gulf of Mexico, 

 using a very sensitive plate and giving an exposure 

 of twenty-four hours. The temperature has a con- 

 siderable influence on the emission of light, though 

 this varies with different species. Thus some 

 remain luminous when cooled as low as — 14° C, 

 while others become inactive below + 15° C. 

 Again, some thrive best at 30° C, while others 

 cease to emit light between 20° and 30° C. The 

 presence of oxygen is an essential for the pro- 

 duction of luminosity, for, although some of the 

 bacteria can be grown in the absence of air, the 

 colonies do not become phosphorescent. Cultiva- 

 tions made in the dark are luminous, so that 

 sunlight does not appear to be an essential factor 

 Lehmann and Tollhausen regard the production of 

 light as a vital process, due to internal molecular 

 changes of the cell ; and this view receives support 

 from the fact that all chemical agents, such as acid 

 or alkalies, which destroy the cellular protoplasm 

 also put an end to the phosphorescence. On the 

 other hand, it is not improbable that the phos- 

 phorescence originates from an excretory product 

 of the bacteria. It is further interesting to note 

 in this connection that Dubois extracted from the 

 mantle of the luminous mollusc, PTtolas dactylus, 

 two crystalline phosphorescent compounds, to one 

 of which he gave the poetic name of luciferase. 



Mate or Paraguay Tea. — Pure Mate" is sup- 

 posed to consist entirely of the leaves of the Ilex 

 parayuayeoisiSi which have a green colour and a 

 characteristic aromatic smell. Much of that sold 

 in Europe, however, is mixed with the stalks of 

 the plants which contain none of the alkaloid 

 caffeine, and are therefore valueless as stimulants. 

 It is stated by Katz that the young leaves of Ilex 

 aquifolia have been used for some time past in the 

 Black Forest in the place of Chinese tea. Mate 

 yields its soluble constituents to boiling water 

 with much less readiness than tea, but the whole 

 of the caffeine and most of the tannin is easily 

 extracted. The amount of caffeine is about 1 per 

 cent., and is thus much less than is present in tea. 

 The ash from the extract of mate leaves contains 

 a high percentage of manganese and magnesium 

 salts, to which it is thought the plant probably 

 owes some of its physiological properties. 



Estimation of Dust in the Air. — An in- 

 genious apparatus has been devised by Karl Arens 

 for this purpose. It consists of a glass tube 

 loosely packed with a layer of cotton wool and 

 connected with an aspirating apparatus on the 

 principle of the bellows. The dry tube and wool 

 are weighed, and after a given volume of air has 

 been drawn through are allowed to stand for 

 twenty-hours over strong sulphuric acid, which 

 attracts the moisture from the wool, and is again 

 weighed. The whole of the dust is retained by 

 the wool and its amount is shown by the increase 

 in weight. In this way the subjoined results were 

 obtained in milligrammes to a cubic metre in the 

 places mentioned: — Dwelling-room, — ; laboratory, 

 T4 ; schoolroom, 10 - ; horse-hair factory, 17'0 ; 

 sago factory, 17 and 15 ; woollen factory, picking- 

 room, 7'0 ; ditto, cutting-room, 20 - ; flour-mill, 

 22 and 28 ; iron foundry (15 to 20 workmen), 

 28-0; ditto (not previously used), 1-5; ditto (few 

 workmen), 12'0 ; ditto (during interval), 8-0 ; 

 snuff factory, 72-0 ; ditto (before grinding), 16 -0 ; 

 cement works (during work), 224 - ; ditto (in an 

 interval), 130-0. 



