34 JELLY-FISH, STJLB-FISH, JLN'D SEA-UBCHIXS. 



other words, but for the sake of symmetry, I might 

 as well have stated at the first that in the case of 

 the oovered-eyed Medusae all the remarkable para- 

 Ivzintr effects which are obtaine<l hv excising the 

 entire margin of an umbrella are obtained in exactly 

 the same degree by excising the eight lithocysts 

 alone ; the intermediate marginal tissue, in the case 

 of these Medusse, is totally destitute; of locomotor 

 centres. 



Eg^tds upon the Manuhrium of exci^irig the 3Iarjin 

 of a Isedocalyx or UmhreUa. 



Lastly, it must now be stated, and always borne 

 in mind, that neither in the case of naked nor 

 covere<l eyed Medusae does excision of the margin of 

 a swimming organ produce the smallest effect upon 

 the manubrium. For hours and days after the 

 former, in coni^equence of this operation, has ceased 

 to move, the latter continues to perform whatever 

 movements are characteristic of it in the unmuti- 

 lated orc^anism — indeed, these movements are not 

 at all interfered with even by a complete severance 

 of the manubrium from the rest of the animal In 

 many of the experiments subse(juently to be 

 detailed, therefore, I began by removing the manu- 

 brium, in order to afford better facilities for 

 manipulation, 



SvLmraary of Cttapier. 



With a single exception to hundreds of observa- 

 tions upon six widely divergent genera of naked- 



