ON COLOURING MATTERS OF VARIOUS ANIMALS. 
15 
troscopically. The spectra are figured in the accompanying 
woodcut. 
1 
3 
Fig. 1 represents the spectrum obtained from a species of 
Mopsea dredged from 600 fathoms. The light', as usual, 
rvas 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 
obtaiued 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 Unibellula 
from 2500 fathoms. Here also the light was greatly increased 
by the action of fresh water. 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 rvas 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 effects of various forms of stimulus on the amount of 
li°ht produced seems in these deep-sea Alcyonarians to agree 
wtth those to be observed in the case of similar shallow- 
water forms. 
General Remarks. 
My friend, Professor Lankester, in his long series of 
observations on animal colouring matters, published at 
various times, 1 seems to have been somewhat unfor- 
> Blue Sleniorin ,—“ The Colouring Matter of Slentor ccertdcus,” by E. 
