Miscellaneous. 815 



Darkness came on without bringing about the wished- for object ; but 

 to profit by my last night's disappointment, I placed the aquarium 

 on the table, raised to a convenient height for inspection, bringing 

 the gas to bear effectually upon it by means of a flexible tube ; and, 

 so far as the facility of inspection went, all seemed right, with little 

 probability of disappointment. Believing that it could not remain 

 long without the support of more fibres, and to awaken it to a sense 

 of that necessity, I agitated the water by rocking the jar slightly 

 from side to side. But I began to perceive, to my dismay, that the 

 water was in an unhealthy state ; I replaced it with an artificial 

 mixture, in which all appeared to revive. Next morning all seemed 

 to be again healthy, yet the mussel had thrown out no new fibres 

 since I cut the four. By the afternoon, I had got a new supply of 

 sea-water, and substituted it for the artificial, which gave a renewed 

 stimulus to the whole. I now observed that the motions of the 

 mussel were frequent : after a short time, it threw out, with consi- 

 derable force, two small, well-defined streams of milk-like fluid from 

 an aperture at the posterior margin of the anal current, which shot 

 like two silvery wires through the water, then gradually opened and 

 broke up into a beautiful shower of feathery-looking flakes pre- 

 cipitating rapidly to the bottom. The streams continued at intervals 

 for about a quarter of an hour, and towards the end, when more 

 scanty, they became finer and single. I believe the white matter to 

 be ova, I subjected it to the microscope, and found it composed of 

 little transparent globules, filled with granular matter surrounded by 

 a delicate membrane, and, when ruptured, the contents flowed out 

 freely. At the close of the milky discharge, the animal became more 

 restless, and the valves opened more widely. The foot now began to 

 protrude and feel about, and fixed for a few seconds on the jar, then 

 darted in with great force : it seemed to be very sensitive, often 

 withdrawing from a slight touch on its own fibres ; again the foot 

 protruded more than an inch, and fixed to the jar ; the animal now 

 began to move forcibly up and down, as if endeavouring to drag itself 

 from the byssus ; the peduncled attachment was seen at every pull 

 rising above the valves of the shell ; these motions lasted about five 

 minutes, the foot still adhering to the glass, when, to my joy, I saw 

 a very fine fibre stretched up by its side, and a white spot coming 

 distinctly into view under the tip of the foot. 



I have since placed other mussels in separate jars, and cut all the 

 byssus close by the shell ; in five hours afterwards, some had three, 

 others four and five fibres ; next day, one of them had eighteen fibres ; 

 and again the following day one of them had cast its byssus, and had 

 attached itself three inches farther up the jar by the new fibres be- 

 fore it disengaged itself from the old. I have now often seen the 

 fibres fixed ; the part of the foot that performs this office is at a 

 point a little below the apex. When more than one fibre is attached 

 at a time, the lower one is fixed first, then the foot is pushed a little 

 farther up on the same line, and a second and a third are fixed in the 

 same way ; but I have never seen more at a time than three, some- 

 times two, and often only one. 



