98 THE LIMIT OF THE PERSISTENCY 



tunate in discovering the origin of another, or rather of several 

 forms of these pseudo-animate bodies called Infusoria. Whilst 

 watching the decomposition of the inner wall of the proboscis 

 of a young Aurelia flavidula, our common Jelly-fish, I observed 

 that the whole component mass of cells was in violent agitation, 

 each cell dancing zigzag about within the plane of the wall. 

 If any one will shake about a single layer of shot in a flat pan 

 he can obtain an approximate idea of the appearance of this 

 moving mass. In a perfectly healthy condition these cells lie 

 closely side by side, and do not move individually from place to 

 place, but yet are active on one side, which constitutes the sur- 

 face of the stomach, where they are covered by vibratile cilia. 

 As the young Aurelia grows, this wall becomes separated from 

 the outer one, but not completely, for the cells of the two adhere 

 to each other by elongated processes varying in number from 

 one to six or seven. Each cell of the inner wall contains numer- 

 ous red or brown granules, a few transparent globules, and a 



single large clear mesoblast (nucleus). 

 When decomposition ensued, these cells 

 became still farther separated from each 

 other (fig. 50) and danced about in the man- 

 ner which I have just described. The vibra- 

 tile cilia were not observed to share in this 

 movement ; in fact I could not detect their 

 presence, because, no doubt, they had 

 become decomposed and fallen away ; but the elongated pro- 

 cesses, which heretofore had remained immovable and stiff, 

 lashed about with very marked effect upon the cells to which 

 they belonged, and caused them to change place constantly. 

 At last the inner wall fell to pieces, and every cell moved in- 

 dependently and in any direction." 



Since that time I have made similar experiments with the 

 muscle and tendon of various animals, and among others those 



Fig. 50. Aurelia flavidula. Per. and Les. 1000 diam. Cells, from the 

 decomposed inner wall of the Ephyra, with their elongated, pointed processes 

 lashing about with great activity, n, the nucleus. Original, 



