NOTES. 421 



Medusae, Polyps, Worms, Timicata, &c. Phosphorescent fishes have 

 been brought to our knowledge by the ' Challenger ' expedition. Wille- 

 moes was able to observe directly the phosphorescence in Sternojjtyx ; 

 and according to Giinther (see below) it is highly probable that the 

 peculiar organs occurring in blind fishes are phosphorescent. The fisher- 

 men of Nice assert that the moon-fish, Ortliagoriseus mola, is luminous. 

 But few phosphorescent animals live on land ; only a few Myriapoda and 

 Annelida, besides the well-known Lampyris, Elateridse, &c. The litera- 

 ture of the subject is wonderfully extensive ; Ehrenberg, who gave more 

 attention to it than almost anyone else, in the lait year of his life gave 

 us a work with the following title : Die das Funlieln wid Av/bliUen ties 

 Mittelmeeres bemirluinden unsicJitbarea Leben^irrmen (Berlin, 1873). 



Nate 23, page 86. The anatomy of the fishes in which Gunther found 

 these phosphorescent organs is not yet described, and I owe the notice I 

 am enabled to give to a verbal communication from my esteemed 

 friend in London. 



Note 24, page 89. See on this subject the brief remarks in Sir 

 Wyville Thomson's Tlie Depths of the Sea (ed. 2, p. 465). Many 

 observations on the brilliant colouring of Holothuridse and Crustacea 

 occur in Willemoes' reports. This proves that the lack of light cannot 

 directly hinder the development of pigment. But it is quite possible 

 that it may have an indirect influence through modifications in the 

 processes, at present unknown, which lead to the formation of the 

 pigment. 



Note 25, page 89. Higginbottom, ' Influence of Physical Agents in 

 the Development of the Tadpole of the Triton and the Frog,' Phil. 

 Trans. 1850, p. 431. He reared larv* in dark cellars and in com- 

 plete darkness without discovering any difference in their development 

 beyond its retardation by the diminished warmth. 



Note 26, pa^e 91. Within the last few years I have repeated a series 

 of experiments with a view to investigating the effects of different 

 light on the formation of pigment in animals ; the creature selected for 

 the purpose was the Axolotl. The more general results attained by 

 these experiments are given in the text. The origin of the pigment 

 does not depend directly on light, as Bert states, nor do albinos or white 

 Axolotl occur in the dark. It remains a mystery to me how Bert could 

 have ascribed the occurrence of white Axolotl to the influence of a 

 deficiency of light, and I am equally ignorant^as to the causes which 

 led to the production of albinos among the Axolotl kept by KoUiker at 

 Wtirzburg. 



I found, precisely on the contrary, that when the light was ex- 

 cluded, or in a dark red light, the young animals were always dark- 

 coloured ; in a yellow light the pigment was abundant though less 

 dark ; in a white diffused light, but to the exclusion of the direct rays 

 of the sun, they were of a much lighter hue, but still not white. 



