ON COLOURING MATTERS OF VARIOUS ANIMALS. 



15 



troscopically. The spectra are figured in the accompanying 

 woodcut. 



Fig. 1 represents the spectrum obtained from a species of 

 Mopsea dredged from 600 fathoms. The light, as usual, 

 was emitted very- vividly on the animals being put into fresh 

 water, but, as usual, soon exhausted under the influence of 

 this stimulus. 



Fig. 2 represents the spectrum yielded by a Virgularian 

 obtained from 1090 fathoms. The yellow was in this case 

 especially brilliant. Portions of phosphorescent tissue were 

 readily detached from the specimen. The light was greatly 

 increased on the tissue being squeezed or rubbed. 



Fig. 3 gives the spectrum obtained from an Umbellula 

 from 2500 fathoms. Here also the light was greatly increased 

 by the action of fresh Avater. The specimen was placed first 

 in fresh water, then in salt water, and finally in spirit. Very 

 vivid light was emitted as it came in contact with the spirit. 

 The whole stem was phosphorescent. 



It will be remarked that the light emitted by the Um- 

 bellula consists solely of yellow and green light, whilst both 

 of the other Alcyonarians produce a considerable quantity 

 of red light. The Virgularian gives out more red light than 

 the Mopsea ; the Mopsea, on the other hand, making up for 

 the deficiency by showing more green. 



The efi'ects of various forms of stimulus on the amount of 

 light -produced seems in these deep-sea Alcyonarians to agree 

 with those to be observed in the case of similar shallow- 

 water forms. 



Geneeal Remarks. 



My friend. Professor Lankester, in his long series of 

 observations on animal colouring matters, published at 

 various times,^ seems to have been somewhat unfor- 



\ Blue Stentorin. — "The Colouring Matter of Stentor candeus" h^ "E, 



