206 
THE CANADIAN NATURALIST 
Noctiluca ) its purpose is to direct the winged male to the 
wingless female. But it is surely forgotten that other insects 
have no difficulty in finding the females which are stationary^ 
but that^ on the contrary^ they possess a peculiar power of 
discovering them_, even when totally concealed from sights as 
when enclosed in boxes^ and even coming down chimneys^ 
and beating against windows^ to obtain access to them ; on 
which power, the plan of taking males, called sembling/* 
is founded. And whether or not, the explanation of the 
phenomenon would not answer in this instance, where both 
sexes are winged. 
C. — It is not without a parallel in other insects, such as 
some Elaters and Fulgor(E ; and in those very curious mol- 
lusca so abundant in the ocean, which make the ship's path 
a path of light and splendour. Have you ever observed these 
marine illuminations with any attention ? 
F,- — I have not had any opportunity of making micro- 
scopic observations on them ; but my curiosity and attention 
have often been excited by the appearances, and I have 
occasionally made some notes on their peculiarities. In 
crossing the Atlantic from Newfoundland to England, I 
have noticed three distinct kinds of light in the water, all 
visible at the same time. One was the cloudy, milky ap- 
pearance of the sea under the stern and in the wake, just as 
if the ship had disturbed a quantity of chalk at the bottom : 
another kind consisted of an innumerable multitude of mi- 
nute bright sparks, appearing at the sides of the vessel, and 
among the former cloudy light, though perfectly distinct 
from it. These two sorts appeared to be caused by the 
ploughing of the ship through the water, but the third sort 
was evidently quite independent of this cause. It may be 
described as broad flashes of light on the surface of the waves, 
coming and going like sudden fitful flashes of lightning. 
