452 THE NATURAL HISTORY 



and kept them some time in glass jars partially rilled 

 with water. Under these circumstances, we had ex- 

 cellent opportuni'ties of watching their proceedings in 

 the manufacture of their wonderful mid-water diving 

 bells, their mode of supplying them with air, their 

 activity in pouncing upon flies thrown on the surface, 

 and their beautiful appearance as they progressed 

 through the water, each in a brilliant silvery envelope 

 of air. Here, too; when they Vere in the act of glueing 

 their lines to the inner surface of the glass, we could 

 with the greatest ease examine through a lens the 

 curious and complex action of their spinners, each of 

 the latter working independently of the others, and 

 each producing a distinct thread, which remained per- 

 manently separate from the main line when finished, 

 a short but appreciable distance from the glass. As, 

 however, these and other details of the economy of 

 Argyronetra, if not widely known, are within easy 

 observation of any one possessing an aquarium, we 

 need not dwell on the subject. 



Every one is familiar with the white flocculent 

 masses of gossamer that on a fine dry day in autumn 

 may be seen in greater or less abundance gently float- 

 ing in the atmosphere, these are the first balloons of 

 which there is any record, and, simple as they are, they 

 are admirably adapted for facilitating the dispersion, or 

 partial migration of spiders. Some naturalists believe 

 that there is a distinct species of so called Gossamer 

 spider, but many others assert that several species of 

 different genera are engaged in the manufacture of this 

 substance, which consists primarily of a viscid fluid 

 expelled by them in such a position that, according to 

 Mr. Blackwall, the eminent Arachnologist, it is " drawn 

 out into fine lines by the ascending current occasioned 

 by the rarefaction of the air contiguous to the heated 

 ground. Against these lines the current of air im- 

 pinges till the animals, feeling themselves acted upon 

 with sufficient force, quit their hold of the object on 



