On the Nervous System of Actinia. 67 



not in all, are also called chromatopbores and " bourses marginales " ; 

 and tbeir beautiful turquoise colour bad rendered tbem attractive 

 to previous anatomists, wbo bad, as bas already been noticed, guessed 

 concerning tbeir function. 



Homard determined tbat tbey were folded elements of tbe skin 

 in wbicb tbe capsules (nematocysts) were enormously developed. 

 He stated tbat tbe tbread of tbese gigantic nematocysts was seen 

 witb difficulty. He noticed tbe transparency of some large cells in 

 tbe bourses, and stated tbat, in bis opinion, tbere was " some 

 pbysiological relation between tbese little organs and tbe ligbt." 



Jules Haime (probably in 1855) examined tbe minute anatomy 

 of Actinia mesemhryanihemum, and bis colleague, Milne-Edwards, 

 quotes bim in tbe ' Hist. Nat. des Coralliaires,' vol. i., p. 240. Tbe 

 lamented young naturalist found out tbat tbe cbromatophores bore, 

 so far as tbeir number is concerned, a decided numerical relation 

 witb tbe number of tbe tentacles. He decided tbat tbey contained 

 but few muscular fibres, and bad navicular-sbaped nematocysts, 

 "diversement contourncs," witb indistinct tbreads witbin tbem. 

 However, be recognized large transparent cells and pigmentary 

 granules in tbem. Tbe nematocysts of tbe cbromatopbores are 

 larger tban tbose of tbe tentacles. He was evidently not satisfied 

 witb tbe data upon wbicb tbese coloured masses were decided to be 

 of importance as organs of special sense. In all probability Haime 

 was aware of Homard 's work. 



Kolliker and tbe German bistologists added about tbis time, 

 and later, to tbe exact knowledge respecting tbe bistology of tbe 

 muscles, skin, endotbelium, and tentacular apparatus, but no advance 

 was made towards tbe discovery of a nervous system in tbe Actinia 

 for many years. 



In i871 tbe popular idea of tbe extent of tbe nervous system in 

 Actinia was expressed by Alex. Agassiz,* wbo wrote: — "Notwitb- 

 standing its extraordinary sensitiveness, tbe organs of tbe senses in 

 tbe Actinia are very inferior, consisting only of a few pigment cells 

 accumulated at tbe base of tbe tentacles." 



But in tbis year a great advance was made towards discovery by 

 Profs. A. Scbneider and Eotteken.f Tbe first-named naturalist paid 

 especial attention to tbe development of tbe lamellse and septa in 

 Corals and Actiniae, and bis colleague laboured in tbe bistology of 

 Actinia especially. 



Working at a very great disadvantage, witb specimens wbicb 

 bad been preserved in alcobol, Eotteken produced a series of 

 researcbes wbicb added greatly to tbe knowledge already granted to 



* 'Sea-side Shidies,' Eliz. and A. Agassiz, 1871, p. 12. 



t Sitzungsbericht der Olierliessischeu Gesellschaft fUr Natur- und Heilkimde, 

 March, 1871 (On the Stniotuie of Actinia' and Corals). Translated for the 'Ann. 

 and Mag. of Nat. Hist.,' 1871, vii., \\ 437, by W. S. Dallas, F.L.S., &c. 



