340 EVENINGS AT THE MICROSCOPE. 



the unassisted eye. But by the aid of the lens you see 

 that each line is a long and slender thread, which creeps 

 along the glass, and at length starts out from it free for a 

 short distance, and is then terminated by a long club- 

 shaped body, which carries at its extremity four horizon- 

 tally divergent organs, like the arms of a turnstile. Tracing 

 down the threads to their lower extremities, you see that 

 they are branches of one thread, which creeps irregularly 

 over a filamentous sea-weed growing from a stone in the 

 jar. The sea-weed had been in the vessel for several 

 weeks, and the water having been undisturbed, the knobbed 

 thread, which was originally confined to the plant, con- 

 tinued to grow, and, coming into contact with the glass, 

 spread upon it. Many other threads have extended from 

 the creeping root, some of which stand up freely in the 

 water, with their knobbed extremities floating in the 

 wave. 



This is one of the Polype tribe, named Stauridia pro- 

 ducta, and as its form and structure are interesting, we 

 will devote a few moments to its examination. We can 

 easily sever one or two of the freely floating threads, and 

 transfer the amputated portions to one of the live boxes of 

 the microscope. The motions and appearance of the club 

 with its organs will be, for a while, little affected by the 

 violence. 



The long cylindrical thread is enveloped in a transparent 

 horny tube, which, however, so closely invests it, that it 

 is with difliculty distinguished. The club-shaped head, or 

 individual polype, is an enlargement of the thread, which 

 protrudes from the investing tube. It is swollen in the 

 middle and rounded at the end, and many of the heads, 

 which are more ventricose than the rest, contain a bubble 

 of air in the centre. This air is doubtless taken in at the 

 mouth, which is situated at the extremity; for, though 

 you can discern no perforation, yet there is an aperture 

 capable of being opened widely at the pleasure of the 



