STRUCTURE OF THE MEDUSiE. 18 



present in the Medusse is one which has long 

 occupied tlie more or less arduous labours of many 

 naturalists. The question attracted so much in- 

 vestigation on account of its being one of unusual 

 interest in biology. Nerve-tissue had been clearly 

 shown to occur in all animals higher in the zoolo- 

 gical scale than the Medusae, so that it was of much 

 importance to ascertain whether or not the first 

 occurrence of this tissue was to be met with in 

 this class. But, notwithstanding the diligent appli- 

 cation of so much skilled labour, up to the time 

 when my own researches began there had been so 

 little agreement in the results obtained by the 

 numerous investigators, that Professor Huxley — 

 himself one of the greatest authorities upon the 

 group — thus defined the position of the matter in his 

 " Classification of Animals " (p. 22) : " No nervous 

 system has yet been discovered in any of these 

 animals." 



The following is a list of the more impor- 

 tant researches on this topic up to the time 

 which I have just named : — Ehrenberg, " Die 

 Acalephen des rothen Meeres und der Organismvs 

 der Medusen der Ostsee," Berlin, 1836 ; Kolliker, 

 " Ueber die Randkorper der Quallen, Polypen und 

 Strahlthiere," Froriep's neue Notizen, bd. xxv., 

 1843; Von Beneden, "Memoire sur les Campanu- 

 laires de la cote d'Ostende," " Memoires de 

 r Academic de Bruxelles," vol. xvii., 1843; Desor, 

 "Sur la Generation Medusipare des Polypes 

 hydraires," "Annales d. Scienc. Natur. ZooL," ser. iii. 

 t. xii. p. 204 ; Krohn, '' Ueber Podocoryna carnea," 



