TRANSACTIONS OF SECTION D. 1043 
Section D.—BIOLOGY. 
PRESIDENT OF THE SEcTION—Professor W. C. McIntosu, M.D., LL.D., 
F.R.S.L. & E., F.L.S. 
THURSDAY, SEPTEMBER 10. 
The PRresmEnt delivered the following Address :— 
I HAVE selected the subject of the phosphorescence of marine animals for a few 
remarks on the present occasion—the theme, perhaps, being the more appropriate 
from its congenial local surroundings ; for, like St. Andrews, Aberdeen is an 
‘old University town 
Looking out on the cold North sea,’ 
A phenomenon so striking as the emission of light by marine organisms could 
not fail to have attracted notice from very early times, both in the case of 
navigators and those who gave their attention in a more systematic manner to the 
study of nature. Accordingly we find that the literature of the subject is both 
varied and extensive—so much so, indeed, that it is impossible on the present 
occasion to give more than a very brief outline of its leading features. This is a 
subject of less moment, however, since the great microscopist, Ehrenberg, in his 
treatise, ‘Das Leuchten des Meeres,’ published by the Berlin Academy in 1835, 
has given a very full account of the early literature on phosphorescence, both in 
marine and terrestrial animals, no less than 436 authors being quoted. The 
limitation just mentioned is therefore sufficiently warranted. 
Though it is in the warmer seas of the globe that phosphorescence is observed 
in its most remarkable forms—as for instance the sheets of white light caused by 
Noctiluca, and the vividly luminous bars of Pyrosoma—yet it is a feature which the 
British zoologist need not leave his native waters to see both in beauty and perfec- 
tion. Many luminous animals occur between tide-marks, and even the stunted 
seaweeds near the line of high-water everywhere sparkle with a multitude of 
brilliant points. Asa ship or boat passes through the calm surface of the sea in 
summer and autumn, the wavelets gleam with phosphorescent points, or are crested 
with light; while the observer, leaning over the stern, can watch the long trail of 
luminous water behind the ship, from the brightly sparkling and seething mass at 
the screw to the faint glimmer in the distance. On the southern and western shores, 
again, every stroke of the oar causes a luminous eddy, and some of the smaller 
forms are lifted by the blade and scintillate brightly as they roll into the water. 
The dredge and trawl likewise produce, both in the shallower and deeper parts of 
our seas, many luminous types of great interest and beauty. 
I shall, in the first instance, glance at the various groups of marine animals which 
possess the property of phosphorescence, and thereafter make some general remarks 
on the subject. It is found then that this feature is possessed by certain members of 
the Protozoa, and by the following groups of the Metazoa, viz.: Ccelenterates, 
Echinoderms, Worms, Rotifers, Crustaceans, Molluscoids, Mollusks, and Fishes. 
About the middle of last century Baster found that at least three species of 
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