236 SUMMARY OF CURRENT RESEARCHES RELATING TO 



even after having been long preserved in spirit. Its capsnle is of an 

 oblong-ovate form with a projecting tubercle at the hinder extremity, 

 within which the actual body of the infusorian is attached ; it is strongly 

 constricted in the middle, and the aperture is surrounded by a nearly 

 erect or slightly everted collar. It forms an interesting addition to the 

 long list of commensals found on Eupagurus BernJiardus. 



Luminosity of Noctiluca miliaris.* — Dr. L. Plate has lately made 

 a thorough investigation of Noctiluca miliaris. He describes the 

 nucleus as a vesicle bounded by a distinct membrane, the limpid 

 contents of which are sometimes perfectly homogeneous, but which, as a 

 rule, have several nucleoli which are true globules and not threads, as 

 described by Cienkowski. He accepts Biitschli's explanation of the 

 so-called bacillar organ, according to which its ridges are produced 

 merely by a particularly close attachment of the plasma to the body 

 membrane. The formation of swarmers is more frequent than repro- 

 duction by simple division. 



All observers are agreed that the luminosity of Noctiluca may be 

 called forth by any strong irritation, so long as air is not excluded ; as 

 the light is extinguished in nitrogen it seems to follow that the lumin- 

 osity is an oxidation process. Further observations may be adduced in 

 favour of this proposition ; the luminosity occurs only in the peripheral 

 plasma of the body, and regenerating forms, which accumulate at the 

 bottom of a vessel of water, are made to phosphorize^with much more 

 difficulty than normal individuals swimming at the surface, and under 

 the influence of the atmospheric air. When pure oxygen was passed 

 over specimens for some minutes a dull light was produced which was 

 visible for about ten minutes after the evolution of the gas. 



If Noctilucse be laid upon moist blotting-paper and examined under a 

 high power, the light may be found to belong to one of four categories : — 



(1) Lightning-like; intense luminosity of the whole outer layer, 

 immediately followed by darkness. 



(2) The same, but with a faint after-luminosity persisting for one or 

 two minutes. 



(3) Dull luminosity of the outer zones of plasma, or of some consider- 

 able portions of it, with simultaneous strong sparkling of small points. 



(4) A large portion of the surface is entirely or partially luminous, 

 the luminosity being composed of numerous small points. 



This luminosity appears to be involuntary, and induced by external 

 irritation. As to the lighting-up of the sea, it would appear that the 

 wind and the strength of the waves alone exert any appreciable influ- 

 ence ; the light is not so fine when the waves break strongly, as then the 

 Noctilucse are drawn down too far beneath the surface of the water. 



Red Organisms of the Red Sea.-j"— Herr K. Mobius criticizes the 

 theory of Krukenberg that the red colour of the Eed Sea is due to 

 specimens of Noctiluca miliaris; this red colour (hsematochrome) is 

 stated to disappear rapidly in alcohol. As the Noctilucse of the North 

 Sea are always colourless, Mobius suggests that the colour was due to 

 the infusoria having recently eaten Trichodesmium erythreeum, or that 

 specimens of that Oscillarian had got into the bottle with the Noctilucse. 

 We still require to know what substances, if any, of the animal are 



* Zool. Jahrb., iii. (1888) pp. 174-80. Ann. and Mag. Nat. Hist., iii. (1889) 

 PP- 22-8. t SB. Gesell. Naturf. Frennde, 1888, pp. 3-4, 17-18. 



