124 



KNOWLEDGE. 



[JcKE 1, 1895. 



but it is hoped suggestively, the student must be referred 

 to books like Head's " Historia Numorum " and Gardner's 

 " Types of Greek Coins," illustrated works which cover in 

 a scientific way the vast field of Greek numismatics. The 

 subject is one in which the student of the history of the 

 ancients, their politics, commerce, art and religion, should 

 be thoroughly grounded before he can pretend to under- 

 stand the facts, often distorted by literary tradition, about 

 the life of a people from whom we have not a little to learn, 

 and who, at least, will always remain interesting for their 

 own sake. 



I>i)EX TO Plate. 



jrftfre nof othertxise described^ the coins are staters oj silver. 

 1. Lrdia. Electrum. About 700 B.C. Obi:, Striated surface. 

 Jiei\, Incuse impressions. 

 Phocai'a. Electrum. About 600 B.C. Seal. 

 Croton. About 500 B.C. Tripod. 

 Jletapontum. ,, Ear of com. 



jMethvmna. Early otli centm\v. Boar. 



Athens. Tetradracbm. Late .5th ceuturv. Ohr., Head of 

 Athena. Sev , Owl and olive-sprav. 



7. Syi-aeuse. Decadrachni. 480 B.C. Oil'., Female head surrounded 



bv dolphins. Set\, Victorious four-horse chariot. 



8. S_TTacu«e. Deeadrachm by Euainetos. Earlv 4th century. 



Oil'., Head of Persephone surrounded by dolphins. Rer , 

 TictDrious foxir-horse chariot. 



9. Terina. About 400 B.C. Head of Tictorv. 



10. Ehegium. Tetradracbm. Abjut 400 B.C. Oljv., Liou's scalp. 



Sev., Persiuification of the people of Rhegium. 



11. Barca. Tetradracbm. Abovit 400 B.C. Silphium. 



12. Elis. About 400 B.C. Head of Hera. 



13. Amphipolis. Tetradracbm. About 400 B.C. Eead of Apollo (.=) 



14. Cyzicus. Electrum. 4th century. Oic, Head of Aphrodite. 



liev., "Mill-sail" incuse. 



15. Philip II of Macedon. Gold. Obr., Head of Apollo. Sev., 



Two-horse chariot. 



16. Alexander the Great. Gold. Obv., Head of Athena. Sev., 



A'ictory. 



17. Philip. Tetradracbm. Obi:, Head of Zeus. Sev., Eace-horse. 



18. Alexander. Tetradracbm. 04i'., Head of Heracles. Sev., Zeus. 



19. Lysimacbus, King of Thrace (323-281 B.C.). Tetradracbm. 



Obv., Head of Alexander with horn of Animon. Hev., Athena. 



20. Demetrius, King of JIaccdon (306-283 B.C.). Tetradi'acbm. 



Obv., Head of Demetrius, horned. Rev., Poseidon. 



21. Cistophorus-Tetradracbm, struck at Pergamus, 2nd century. 



Obv., In ivy-wreath, clsfa myslica and snake. Her., Bow-case 

 between two snakes 



22. Antimachus, King of Baetria (2nd century). Tetradracbm. 



Head of Antimachus. 



23. Athens. Tetradracbm. About 200 B.C. Oil'., Head of Athena. 



Sev , In olive-wi-eatb, owl on oil-jar. 



COLOUR-PRODUCING BACTERIA. 



By C. A. Mitchell, B.A.Oxon. 



ALTHOUGH the bacteria belong to the vegetable 

 kingdom, the colouring matter known as chloro- 

 I'l'ijU, to which plants owe their green colour, has 

 not been found in them. They may, in fact, be 

 looked upon as low forms of plant life minus 

 chlorojihi/U. Many of them, however, have the power of 

 producing other colouring matters, some of which are 

 strikingly beautiful, and to these micro-organisms the 

 name of chrumogenk bacteria has been applied. They are 

 widely distributed in water, soil, and air, as may readily 

 be proved in the case of the last by leaving moistened 

 bread exposed to the atmosphere for some days, when, in 

 addition to the moulds which form upon it, there will be 

 noticed coloured patches here and there, which, by 

 microscopic examination, will prove to be colonies of 

 micro-organisms. In Prof. Frankland's recent publication* 

 a long list of the micro-organisms which have hitherto 



* " Micro-organisms iu Water," by Percy and G. C. Frankland, 1894. 



been found in water is given, and of these at least seventy 

 species give rise to a distinct colour on cultivation. 



To give anything approaching a complete list of the 

 chromogenic bacteria would be little more than a tedious 

 catalogue of names, and it is, therefore, preferable to select 

 a few typical instances for detailed examination, from which 

 a general idea of the remainder may be gathered. 



Several species are capable of elaborating a red colouring 

 matter, and the coloured substance produced by one variety 

 differs in properties from that produced by another. All 

 shades of red have been observed, from faint pink to bright 

 vermilion and deep blood-red. 



The pinJc Torula, an organism allied to the yeasts, is 

 frequently met with in the air, and forms a rose-tinted scum 

 when grown on bread paste. It has large round or ovoid 

 cells, ofi — 8(x+ in diameter, which, unlike those of true 

 bacteria, are capable of multiplying by budding. The 

 pink colour is only apparent in the mass, for, under the 

 microscope, individual cells appear to contain a yellowish 

 pigment. 



Another well-known chromogenic organism is Bacillus 

 prodiijiosus, which is frequently found in the air, and is the 

 cause of the phenomenon, which has occurred at various 

 times, of bread or grain assuming a blood-red colour. This 

 is the probable explanation of the miracles and portents 

 of the sort which were once firmly beheved in. The 

 micro-organism was formerly described as a micrococcus, 

 since it is almost as broad as long, but it is now usually 

 classed among the baciUi. It is about 1-o/a in length by 

 l(u. in breadth, and two or more individuals may occasionally 

 be noticed hanging together in chains. On whatever 

 medium grown, the pigment produced is the same, and 

 the colony usually appears as a rich crimson layer on the 

 surface of the cultivation. 



The bacillus is generally stated to be non-pathogenic, 

 but it has been shown by Grawitz and De Bary that the 

 introduction of large quantities of the pure cultivation 

 into the blood of animals sets up symptoms of inflammation. 



The colouring matter is soluble in alcohol and ether, 

 but insoluble in water. With dilute acids it becomes light 

 red, but the origmal colour is restored on adding an alkali. 

 It appears to be closely connected, though not identical, 

 with the aniline colour fuchsinc. 



In 1888, Dr. Edington published a paper on the nature 

 of " red " cod. In the previous year a large consignment 

 of the dried and salted fish had arrived at Lerwick, having 

 on their inner surface, and especially among the particles 

 of salt adhering to them, minute red pomts which resembled 

 little particles of vermihon. On investigation it was 

 found that, although several species of bacteria could be 

 isolated, the one which produced the red coloration 

 was a bacillus, to which its discoverer gave the name of 

 r>. ruhcsrens. When grown on nutrient jelly, a wrinkled 

 colony was formed, in which the pink colour only developed 

 after some weeks. The bacillus was found not only in the 

 fish, but also on the salt used by the curers, showing that 

 salt is not so strong a preservative as is often supposed. 

 Though the organism was proved to be in itself harmless, 

 the fact of its being present at all showed that the fish were 

 insufficiently preserved, and might thus readily become 

 a culture medium for pathogenic species. 



A peach-coloured organism, Bei/'jicitoa roseo-persirina, was 

 discovered in 1873 by Prof. Lankester, in water containing 

 dead animal matter. During its life-history it passes 

 through several forms, the most characteristic of which is 

 a long spiral. It is usually the cause of the blood-red films 

 which may sometimes be observed in pools and marshes. 



tlfi = 



: of an inch. 



