WORMS. 



of tlie most interesting classes of animals 

 is certainly that of Worms. Who has not heard 

 of the wonderful power of reproduction or re- 

 generation of lost parts manifested by the 

 Na'is, those curious little organisms which, in 

 clusters of myriads upon myriads, form those large 

 red patches on the muddy banks of the Thames or 

 other rivers, and which vanish like magic when a 

 stone or stick is thrown upon them ? Cut off the 

 head of one of these little fresh- water worms eight 

 successive times, and you will find that it grows 

 again seven times; the eighth decapitation has 

 proved too much for the reproductive power of the 

 Ndis, and this time the head has disappeared for 

 ever ! The number of times the head will be repro- 

 duced depends upon the vital powers of the indi- 

 vidual submitted to experiment. Bonnet, in his 

 " Observations sur les Yers d'eau douce/' states 

 that he cut a Na'is into twenty- six pieces, and each 

 piece became a new worm. He produced thus 



