1876 MEDUSAE 27 



plants I have operated on, and I have not had time 

 to do anything with animals since I left London. 



The Medusae have now come on in their legion, 

 and occupy my undivided attention. The results so 

 far have proved as definite as they are interesting 

 and important. The following is a summary of the 

 principal. 



All genera of naked-eyed yet examined become 

 immediately and permanently paralysed (except 

 polypite) upon excision of margin, but not so with 

 the covered-eyed. 



The organism thus mutilated responds with a 

 single contraction to a nip with the forceps, also to 

 various chemical stimuli. The chain of ganglia do 

 the same, and further resemble the mutilated organism 

 in contracting once to both make and break of direct 

 or of induced shock. They differ, however, in one 

 important particular : the severed margin retains its 

 sensibility to the induced shock much longer than to 

 the direct, while with the necto-calyx the converse 

 is the case — the latter responding vigorously to make 

 and break of direct current after it has ceased to be 

 affected by even interrupted current with secondary 

 coil pushed up to zero (one cell). 



A strange and, so far as I am aware, an unparalleled 

 phenomenon is sometimes manifested by Sarsia after 

 removal of ganglia. It only happens in about one 

 case out of ten, and never except in response to either 

 chemical or electrical stimulation. A bell quite 

 paralysed, and which may have responded normally 

 enough to stimulation for a number of times, sud- 

 denly begins an active shivering motion, which may 



