20 
ANIMAL LIFE ON THE 
a cavity at the base of the foot, and is composed of a bunch 
of silky filaments, which are capable of being reproduced if 
destroyed. 
A difference of opinion exists amongst naturalists re- 
garding the propagation and nature of these filaments. 
Some contend that the byssus is simply a bunch of silken 
threads woven by the foot of the mollusc, others that it is an 
assemblage of muscular fibres dried up in one part of their 
extent, still contractile and in a living state at their origin, 
a condition which they enjoyed their whole length at the 
period of attachment. 
From recent observation, I am of opinion that the fila- 
ment is due to a gelatinous amber-coloured liquid, capable 
of being exuded from the body when required through the 
orifice of the byssus, having no life nor power in any part 
of its length. When the object to be attached is reached by 
the liquid, guided by the foot, the exudation, being dammed 
back, instantly ceases to flow, and adhesion at once begins, 
and through the chemical action of the water, the whole 
length of the filament is quickly converted into the tough 
fibrous substance it is found to be. 
In a small aquarium in my possession I recently dropped 
a mussel, denuded of its byssus, in order to watch the 
reproduction and growth, having previously deposited a 
purple-lip, or dog-wilk, and a common black winkle. Next 
morning, after an interval of eight or ten hours, I was 
astonished to observe the mussel floating, or suspended, 
within two inches of the surface; but how it had gained the 
position, and remained there, I was at first puzzled to know ; 
ultimately, however, I had the mystery explained. The 
dog-wilk, wearied of its lowly position, mounted the glass 
and travelled upwards until its foot rested clear of the 
water, and there remained. The winkle followed suit ; but 
