Watching a Mussel. 141 



steps in ascending, nor seemed in any way doubtful 

 of the stability of his footing. I watched all day 

 patiently, but no more fibres ; after dark, I made my 

 observations only occasionally, and by candle-light, 

 the gas being too distant for minute inspection. 



" Returning on one of these visits, after an absence 

 of an hour, I found four new fibres affixed. This was 

 a great disappointment, to lose, by this short absence, 

 a sight I had so much wished to see. Next day there 

 were no more new fibres, and, as it had seven, it 

 might not be in much want of more. To reduce it 

 again to the necessity of making a new supply, I cut 

 four, leaving three, and I again set to watch with 

 renewed zeal. 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 inspec- 

 tion 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. 



