346 ORGANIC GROWTH 



contract feebly, while yesterday no spontaneous movement, 

 and scarcely any reaction to stimulation were observed in 

 this specimen. The Medusa, therefore, has recovered itself 

 in certain parts only ; in these parts vicarious centres of con- 

 traction must have been established, the action of which does 

 not extend beyond their boundaries. The specimen still lies 

 flat and extended, while M when contracting assumes com- 

 pletely the bell-like shape. Three-quarters of an hour after 

 the addition of clean water, contracts at intervals of 2, 1|, 

 1| minutes the same two anal lappets as before. M contracts 

 very actively. Both behave almost in the same way as in the 

 old water. 



Fifth day. 2d September. M contracts actively in the old 

 water ; lies still and begins to decompose, only the two anal 

 lappets which yesterday contracted spontaneously are still 

 entire. The other anal lappets have dissolved away, except 

 two, pieces of which are still left. 



Sixth day. 3d September, 8.30 A.M. Only some of the 

 separated pieces of which contain marginal bodies are left 

 alive, all the rest is in process of dissolution. Putrefaction in 

 the vessel, which has also caused the death of M. 



Seventh day. 4th September. The fragments containing 

 marginal bodies alive yesterday are still alive, but are reduced 

 to narrow ('75 cm. broad) strips, and each is merely a mar- 

 ginal body with a morsel of the umbrella margin connected 

 with it. 



Eighth day. 5th September. One fragment of the margin 

 with its marginal body still alive and contracting, although 

 the water is completely putrid from the decomposing Medusa 

 left in it all night. 



In this case, therefore, two new nerve-centres came 

 into action in two portions of a Medusa while the rest was 

 dying, and these centres, when the living portion of the body 

 was stimulated, produced contraction in the anal lappets con- 



