i88 5 .] 
Luminous Phenomenon round the Sun. 
45 
Two perches were blinded by removal of the eye-ball. 
There remained to them, then, for guidance, merely the 
general sensibility of the integuments and the special im- 
pressionability of the lateral apparatus in question. These 
organs acquire in a short time a great delicacy, for the two 
perches when placed in the general aquarium were soon 
able to guide themselves without any difficulty. 
But the question now arises as to what part of this 
steering-power belongs to the general sensibility, and what 
to this lateral line ? Further experiments solved this 
problem. 
A barbel was blinded, and, by way of extra precaution, its 
filaments were amputated. Subsequently its lateral nerve 
was severed. As long as this fish — even though deprived of 
its eyes and beard — retained the lateral nerve it guided itself 
easily ; but as soon as this nerve was severed it remained 
persistently motionless. 
Lastly, a perch, blinded and deprived of its lateral line on 
one side only, was placed in the labyrinthine aquarium. It 
contrived to keep the non-mutilated side turned towards any 
obstacle, 
These experiments leave no doubt as to the function of 
the lateral line. 
It is a very delicate organ of touch, adapted to the re- 
quirements of an aquatic life. It is sensitive to the faintest 
movements of the water, takes cognisance of the slightest 
displacements, and gives fishes continual information on the 
state of the medium in which they live. 
LUMINOUS PHENOMENON ROUND THE SUN. 
Herr J. G. Walter, of Bremen, writes thus to the Editor 
of the “ Naturforscher ” : — 
“ The memoir of M. Forel, in your paper of October nth, 
concerning Luminous Appearances round the Sun, leads me 
to communicate my own observations on this phenomenon. 
“ After the intense evening red of last winter had ceased, 
and whilst nothing remarkable appeared in April and May, 
I remarked in June daily here, in Bremen, a yellowish brown 
halo round the Sun. During July, August, and September 
