748 THE POPULAR SCIENCE MONTHLY. 



comes a root (Fig. 18) ; and a bud, m, soon grows out from it to form 

 the first feeding hydra, which soon acquires a mouth (Fig. 19, I) 

 and tentacles, i, and begins to capture and digest food and to accu- 

 mulate a reserve of nutriment, while the root continues to throw 



Fig. 18. 



out new buds, as shown in Fig. 18 at m. For a long time all the 

 buds become feeding hydras ; but at last, when the mouths are 

 numerous enough, buds which remain mouthless are formed, and 

 become the blastostyles or jelly-fish producers. The following 

 diagram shows the life-history of Eutima : 



( Feedins hvdra x i ^lastostyle x j Medusa < eggs. 



VI. Eutima. — ) ° •' { Feeding hydra \ Medusa < eggs. 



Egg = Planula = Boot x 1 ^ , ^^^ ^ j Feeding hydra \ Medusa < eggs. 



^ ° •' / Blastostyle x ( Medusa < eggs. 



Diagram No. 1, which was given in the beginning of this arti- 

 cle, to illustrate the life of Dysmorphosa, shows the next stage in 

 the process of complication, and a comparison will show that it is 

 derivable from Diagram VI by slight changes, just as VI is deriv- 

 able from V, and this from the preceding, and so on until finally 

 we reach a simple, direct life-history, in which each egg produces 

 one adult, which passes through a transitory larval hydra stage. 



Forty years ago, a zoologist of the old school might have be- 

 lieved that the life-history of Dysmorphosa has always been com- 

 plex, and that of Liriope always simple ; but the doctrine that all 

 the representatives of any great group of animals owe their com- 

 mon characteristics to descent from a common ancestor is one of 

 the fundamental principles of modern elementary zoology, and as 

 this doctrine forms the basis rather than the aim of this article, 

 I assume, without discussion, that the remote ancestors of Liriope 



