THE FIGURES. 119 



Figs. 18, 19. Individuals much older, and possessing 

 the full number of tentacles ; smaller individuals 

 are seen upon them, as if arising from gemmae or 

 runners (stolones.) 



Figs. 20-34 represent the development of the second gene- 

 ration (the medusa larv^) within, the first (the 

 MEDUSA " nurses"), and their comjjletion into 

 perfect medusa. 



Figs. 20-22. Show the commencing development of 

 new animalcules in the posterior part of the body 

 of the polypiform " nurses'; the development causes 

 the appearance of a transverse division of the 

 animal. Fig. 20 is an individual with one trans- 

 verse ruga. Fig. 21 with more, when several germs 

 have become developed. Fig. 22 with many ; the 

 borders of the new animalcules are now free, eight- 

 lobed ; they possess the power of spontaneous 

 motion. The whole set {Strobila) is, however, com- 

 plete, and the " nurse" animal is placed upon the 

 pile of larvcB, as it may be termed. 



Figs. 23, 24. Show how the Mediisa-larvcs detach 

 themselves from the " nurse' animal. Fig. 24 is a 

 bunch or set of larvae, the " nurse" belonging to 

 which has already become detached : (of a natural 

 size.) Fig. 23 is the lowermost part of such a set, 

 and shows how the larvcB rise up from one another, 

 and are finally altogether separated. 



Figs. 25-30. The {ygq Medusa-larvcB^YOQ.QQdi\\\g to their 

 further development. Fig. 25, a larva of the natural 

 size and recently separated. Fig. 26, an individual 

 rather more developed, and Fig. 27, the same seen 

 fi'om beloAv. Fig. 28, a still larger individual (of 



