Notes on Mt/ri'ipoda. ] I* 



car/)op/if(f/i/ft from Oarwcn m'C made the cxaniinatioii of films 

 of material oljtaiiicd in the lighting condition in our liohler. 

 On staining by Gram's metiiod it was at once evident that 

 luminosity was not due to micro-organisms of the ty])e known 

 to occur in the blood of some Crustacea, and that if they 

 were present at all they must be filter-passers. Experiments 

 quoted by Dahlgren (4 a), pp. 23-24, in another connection 

 seem to show that no luminous bacteria are known to him 

 to be filter-passers. 



Thus our attempts to find micro-organisms that could 

 cause luminosity have all failed, and we conclude that 

 luminosity in Geophilus carpophagus appears to be an entirely 

 2)hysico-cftenncal phenomenon. 



The details of our experience in this matter confirm our 

 view. The fresh luminous discbarge from a G. carpophuyuH 

 stained by Gram's method in searcb of micro-organisms was 

 examined under the oil-immersion lens. The appearance 

 was that of innumerable very small (less than 0*75 yu.) 

 granules, round and regular and evenly distributed in the 

 deposit. A few small irregularly distributed round em|)ty 

 spaces were also observed in the mass of stained mateiial. 

 AVcre these very small granules iuciferin granules or " vacuo- 

 lids " of Dubois? Their regularity and minute size 

 suggested a doubt. On the other hand, Would similar but 

 non-luminous fluids exhibit like staining properties? It 

 happened that such questions Mere discussed with Mr. C. \V. 

 Ashton of the Manchester Uoyal Iniirmary, and as an out- 

 come an experiment was performed on the spot. This 

 experiment enables us to give a decisive answer to such 

 enquiries. To a pre[)aration of fresh egg albumin Avere 

 added a few n)elted crystals of pure carbolic acid. A film 

 was made from this l)aeteria-free acid albumin and stained 

 by Gram's method. Vuder the oil-immersion lens this film 

 exhibited exactly similar proi)erties to those of the luminous 

 discharge previously examined. 



The Physical Considerations. 



Rudiuactivity. 



As we turn to the physical aspect of the case, perhaps it 

 will cross our minds at once that radioactivity may he the 

 cause of luminositv. If so, the luminositv would be due, we 

 suppose, to the bombardment of a fiuoi'eseent screen by a 

 discharge from the radioactive material. It follows that the 

 animal, in such circumstances, carries substances in its body 

 which will produce or act as a screen. When our friend 



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