THE PAGE OF NATURE, 133 



within the filaments, consequently the plant is propagated 

 viviparously, each of the articulations giving birth to 

 new filaments, which add new meshes to the net, and, in 

 this singular manner, a single individual often weaves 

 a green net-work covering over the whole surface of a 

 pond. It is not attached to any aquatic plants, but 

 floats freely in the water. It is rare in Scotland and 

 Ireland, but is of common occurrence in ponds and 

 ditches in the middle and south of England. 



Another curious conferva, which departs widely from 

 the normal form, is the Moor Ball or Globe Conferva. 

 It is found occasionally in lakes in North Wales, in 

 Cumberland, and in the Highlands of Scotland. The 

 filaments radiating from a central point form dense round 

 pale-green balls, as if composed of faded silk thread, 

 sometimes four inches in diameter, and having a strong 

 resemblance to the hair balls that are found in the 

 stomachs of goats. They are sometimes employed as 

 pen-wipers in the places where they are found. These 

 balls float freely at a small depth in the water, and are 

 often washed ashore by the waves, where they accumulate 

 in dense masses, and are again covered over with a 

 parasitic confervoid growth. 



In ditches by the waysides, may often be seen large 

 dark-green intensely slimy masses of rigid filaments as 

 thick as horse hair. This is the Zygnema (Fig. 18), 

 one of the largest and most curious of the confervse. 

 Under the microscope, the filaments are found joined 

 parallel to each other by transverse tubes, and marked 

 by articulations longer than broad. They are interesting 

 especially as exhibiting the spiral arrangement in their 



