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SCIENCE 



[N. S. Vol. XLIV. No. 1128 



east central Europe. The Dipylon and the 

 Villanova style representing the earliest phase 

 of the iron age in Greece and Italy, respec- 

 tively, both abound in banded and panel pat- 

 terns, especially the meander and the swastika. 

 (The swastika is supposed to date as far back 

 as the neolithic period.) 



The art of the smith made rapid strides 

 during the Hallstatt epoch. A process was 

 developed of at least superficially hardening 

 a blade of iron, although steel proper was as 

 yet unknown. The engraved ornaments of 

 the bronze age now give place largely to em- 

 bossed patterns produced by hammering. With 

 the epoch of La Tene the art of the third and 

 last great stage (Kriegertum) spread over 

 western and northern Europe. 



The revision is everywhere both conserva- 

 tive and thorough; some thirty pages of ad- 

 denda and references will contribute much 

 toward its usefulness as a source book. 



George Grant MacCurdy 



Yale University, 

 New Haven, Conn. 



THE MECHANISM OF LIGHT PRODUC- 

 TION IN ANIMALS 



It has long been known that the dried pow- 

 dered luminous organs of the fire-fly will glow 

 if moistened with water containing oxygen. 

 No light is given off if oxygen is absent. 

 In a previous issue of Science I pointed out 

 that if we allow this dried powder to stand 

 for an hour in contact with water carefully 

 freed of its dissolved oxygen and then admit 

 oxygen, no phosphorescence is to be observed. 

 It is quite obvious that the photogenic sub- 

 stance has been changed in some way even 

 though no oxidation has taken place. The 

 substance, therefore, which in presence of oxy- 

 gen is oxidized with the production of light, 

 in absence of oxygen is also decomposed but 

 without light production. We have an analo- 

 gous instance in the compound lophin (tri- 

 phenylglyoxaline) investigated by Radzis- 

 zewski. If hydrolyzed in presence of oxygen 

 by alcoholic potassium hydrate, light is pro- 

 duced and benzoic acid and ammonia formed. 

 In absence of oxygen, no light is produced and 



benzaldehyde is formed instead of benzoic acid. 

 The alkali acts as a catalyzer. 



In the fire-fly it is natural to suppose that 

 an organic catalyzer, an enzyme, is concerned 

 in light production and it is the purpose of 

 this paper to point out the fact that the 

 existence of such an enzyme has been defi- 

 nitely proved and to add certain new facts to 

 our knowledge of bioluminescenee. The credit 

 of this discovery belongs entirely to Professor 

 Raphael Dubois, of the University of Lyons. 

 As early as 1884 Dubois made the crucial ex- 

 periments in which he showed that two sub- 

 stances are present in the luminous organs 

 of Pyrophorus noctilucus, the West Indian 

 cueullo, a thermostabile substance, luciferin, 

 which oxidizes with light production and a 

 thermolabile enzyme lueiferase. In 1887 Du- 

 bois showed that the same was true for the 

 luminous mollusc, Pholas dactylus. If the 

 luminous slime from glands on the siphon and 

 mantle of this mollusc are collected in sea 

 water in two test tubes the solutions will 

 phosphoresce for some time. Boil the solu- 

 tion in one tube and the light disappears in- 

 stantly; allow the solution in the other tube 

 to stand until the light disappears spontane- 

 ously. Then if both tubes, now dark, be 

 mixed, the light reappears. The boiled tube 

 contained luciferin but no lueiferase while 

 the other tube contained lueiferase but all 

 the luciferin had been oxidized by standing. 

 On mixing, the two substances were again 

 brought into contact and light resulted. In 

 later papers Dubois has studied especially the 

 properties of the Pholas luciferin and lueif- 

 erase and the results are published in many 

 papers in the 0. B. Acad. 8c. Paris and the 

 C. B. Soc. Biol. He says that luciferin is an 

 albumin having acid properties and an active 

 reducing power. It oxidizes readily with lueif- 

 erase, potassium permanganate, barium perox- 

 ide and lead peroxide, giving off light and 

 forming amino-aeids and minute crystals giv- 

 ing the test for xanthin. 



Lueiferase, on the other hand, has all the 

 properties of an enzyme, an oxidizing enzyme 

 acting in the presence of iron salts, which will 

 oxidize luciferin and also tannin, guaiac, a- 



