464 



Mr. G. J. Romanes on the 



[Jan. 



January W, 1877. 

 Dr. J. DALTON HOOKEE, C.B., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



The following Papers were read :— - 



I. Further Observations on the Locomotor System of Medusae." 

 By George J. Romanes, M.A., F.L.S., &c. Communicated by 

 Prof. Huxley, Sec. R.S., &c. Received November 21, 1876. 



(Abstract.) 



I. Fundamental Obseevations. 



§ 1. Fundamental Ohservations on the Nalcecl-eyed Medusce. — The obser- 

 vation which, in my last paper, I designated the " fundamental observa- 

 tion," has been this year repeated numberless times, both on the old 

 species of naked-eyed Medusae and also on some new ones. The result 

 has been in every case to confirm the rule previously enunciated, namely, 

 that " excision of the extreme margin of a nectocalyx causes immediate, 

 total, and permanent paralysis of the entire organ." 



§ 2. Fundamental Observations on the Covered-eyed Medusce. — Regarding 

 the covered-eyed Medusae, it is necessary to say that I have this year 

 confirmed all the observations which required confirmation from the fact 

 of their having been at variance with, those of Dr. Eimer. I have con- 

 tinued to find that the lithocysts are the exclusive seats of sponta- 

 neity, so far as the " primary movements " are concerned. I have failed 

 to detect the slightest evidence of spontaneity on the part of the " con- 

 tractile zones " ; for, after allowing the animal to recover from the shock 

 consequent upon removal of its lithocysts alone, and then observing the 

 degree of spontaneity it manifested, I was in no case able to perceive 

 that, by now removing all the " contractile zones," this degree of spon- 

 taneity was in the smallest degree diminished. Again, as regards the 

 character of the " secondary contractions " which are manifested by 

 the covered-eyed Medusae after excision of their lithocysts or margin, I 

 have found all my previous statements substantially correct. I am still 

 unable to say that these secondary contractions appear to me either more 

 " feeble " or "inefficient " than the primary ones, or that the former are 

 any more of a " local " character than the latter. Neither can I modify 

 my previous statements as to the time after removal of the lithocysts 

 during which the secondary movements persist. So far have I found it 

 from being true that these contractions " generally cease after a few mo- 

 ments, or, at any rate, after a few hours," that I am now able fully to 



