ItB8 HeiT Peter Schmidt on tlie 



In the year 1889 the naturalist referred to observed a strongly 

 luminous TaUtrus on the sea- shore near Wimereux. A 

 specimen of this animal, which hitlierto had never been 

 observed to possess luminous properties, shone so brightly 

 even by moonlight that it was distinctly recognizable at a 

 distance of several metres. The light was of a greenish hue, 

 and came from the interior of the body, which glowed, not in 

 its various parts, but over the entire surface, even to the tips 

 of the antennge and feet, while the eyes alone formed two 

 black dots upon this luminous background. The luminous 

 individual moved very slowly upon the sand, instead of 

 jumping about energetically like the other non-luminous 

 members of the same s))ecies. On examining a foot belonging 

 to the luminous crustacean under the microscope, it was 

 found that it swarmed with micro-organisms {Micrococcus 

 phosphoreus?) between the muscles, and that the muscles 

 themselves were seriously injured by them, which was a 

 sufficient explanation of the sluggish movements of the 

 ci-eature. Giard also succeeded in infecting with these 

 luminous micro-organisms the healthy non-luminous crus- 

 taceans, and in thereby inducing luminosity in them. The 

 animals became luminous in less than three days, continued 

 to be so for from three to six days, then commenced gradually 

 to become languid and motionless, and perished, as was also 

 the case with the original specimen, after from three to four 

 days more, while their bodies still continued to be luminous 

 for some hours. 



It a])pears to me that the luminosity of the midges (Chiro- 

 nomidpe) can, with the greatest probability, be regarded as 

 belonging to the same category as the case above recorded, 

 which, so far as I am aware, is at present entirely unique; 

 this view is supported by the following points : — 



1. The luminosity appears not in peculiar specially luminous 

 species, but in the most common and widely distributed 

 forms *. 



2. The luminosity is (both in accordance with my own 

 observations, as also with the statements of Alenizyn and 

 Ssorokin) not localized at any one point, but embraces the 

 entire body and all its appendages (legs and antennas). The 

 luminosity is also entirely independent of the will of the 

 animal, and still persists for a long time even in alcohol [vide 

 supra). I have even found a Chironomus which was caught 

 in a spider's web and already partially sucked dry by the 



* The luminous specimens of the species of Corethra brought back 

 by Alenizyn likewise appear to belong to one of the most ordinary forms ; 

 but I did not succeed in determining them more precisely. 



