LUMINESCENCE OF MICROSCOLEX PHOSPHOREUS DOUG. 2OI 



cells of the luminous slime take their origin from the body 

 cavity. The fluid is discharged, however, "from the dorsal 

 pores and from the mouth, which it reaches through the pepto- 

 nephriclia opening into the buccal cavity." These observations 

 show clearly that it is most improbable that the granules alone 

 (Pierantoni's bacteria) may pass through the connective tissue 

 and two layers of muscular system until they reach the glands 

 of the skin as Pierantoni seems to believe. 



The next task was to find out whether the cells or the granules 

 alone have the power of luminosity. To test this the luminous 

 extract, obtained by grinding up the whole animals, which easily 

 passes through ordinary filter paper without loosing its lumi- 

 nescence, was centrifuged for 15 min. The centrifuged fluid 

 in which only granules were seen could be made luminous on 

 addition of a few drops of ether. After filtration through bac- 

 teriological filters, however, no light was observed upon treat- 

 ment with ether. The granules therefore must be regarded as 

 a luminous material in Microscolex. This agrees with Gilchrist's 

 observations on Chilola. 



It was noticed that the power of the ejaculation of the slime 

 is directly proportional to the degree of the irritability of the 

 nervous system. Luminous microorganisms, however, glow con- 

 tinually, and are not affected by nerve stimulation when living 

 in luminous organs of some other forms (in certain fishes and 

 cephalopods). A lowered temperature also affects the lumi- 

 nescence, probably by the lessened irritability which is especially 

 noticeable if the animals be kept for a long time at 8-io C. 

 In connection with this I should like to mention the day-night 

 rhythm of luminescence in Microscolex. It was observed that 

 if stimulated, the animal discharged more easily the luminescent 

 slime during the night than in the daytime. It can be shown 

 that this rhythm does not result from an inhibition by light, 

 because the strong arc lamp and sunlight have no visible effect 

 on luminescence. It is possible that this rhythm may be ex- 

 plained by the general lower irritability of the animals during 

 the daytime. 



Before the characteristics of the luminescence will be discussed, 

 it must be stated that if the properties of the luminous slime be 



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