350 EVENINGS AT THE MICROSCOPE 



throughout its length, at regular distances, with a row of 

 secondary filaments, which project at right angles from the 

 main thread. 



These secondary filaments constitute an important ele- 

 ment in the charm which invests this brilliant little creat- 

 ure. They are about fifty in number on each thread, and 

 some of them are half an inch long, when fully extended, 

 but it is seldom that we see them thus straightened; for 

 they are ever assuming the most elegant spiral coils, which 

 open and close, extend and contract, with an ever-chang- 

 ing vivacity. The animal has a very perfect control over 

 the threads, as well as over the secondary filaments in 

 their individuality. One, or both, are frequently projected 

 from their chambers to their full extent by one impulse; 

 sometimes the extension is arrested at any stage, and then 

 proceeded with, or the thread is partially or entirely re- 

 tracted. Sometimes the secondary filaments are coiled up 

 into minute balls scarcely perceptible, or only so as to 

 give to the main thread the appearance of small beads re- 

 motely strung on a fine hair; then a few uncoil and spread 

 divergently; contract again, and again unfold; or many, 

 or all, interchange these actions together, with beautiful 

 regularity and rhythmical uniformity, repeating the alter- 

 nation for many times in rapid succession. 



The beauty and diversity of the forms assumed by 

 these elegant organs beguile us to watch them with un- 

 wearied interest, and we wonder what is their function. 

 For, with all our watching, this is by no means clear. 

 They are certainly not organs of motion. At times it 

 seems as if they were cables intended to moor the animal, 

 while it floats at a given depth ; or we see them with their 

 extremities spread upon the bottom, to which they appear 



