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The Ciliary Mechanisms on the Gill and the Mode 

 of Feeding in Amphioxus, Ascidians, and 



So/enomya togata. 



J. H. Orton, A.R.C.Sc, B.Sc, 



Naturalist in the. Plymouth Laboratory, 



With Fismes 1-11 in the Text, 



TABLE OF CONTENTS. 



Introduction ............ 



The ilode of Feeding in Amphioxus ........ 



The C'iUary mechanisms on the gill of Amphioxus ..... 



The Ciliation of the Endostyle ......... 



The function of the Wheel Organ and the peri-pharyngeal bands in Amphioxus 

 Recapitulation of the account of the food and respiration currents m Amphioxus 

 The function of the Pharynx in Amphioxus .... 



The Mode of Feeding in Ascidians ...... 



Food-collection in various Ascidians ..... 



Cihary mechanisms on the gill of Ascidians .... 



Comparison of the Mode of Feeding in Amphioxus and Ascidians . 

 The Function of the gland and its ciliated tract in the Branchial Openings of 

 Amphioxus and Ascidians ...... 



The Maintenance of the Pharyngeal spaces in Ascidians and Amphioxus 

 The Ciliation of the gill of Balanoglossus ..... 



Observations on the Ammocoete of Petromyzon fiuviatilis 



The Mode of Feeding in »S'oZe?iomya.<o5ra to .... 



The ciliation of the gill of Solenomya ..... 



Resemblance of the ciliation of the gill in Solenomya and Nucula . 



Summary of the account of the ciliary currents in Solenomya 



The function of the gill in Lamellibranchs ..... 



Appendix .......... 



Summary ....... . . 



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INTEODUCTION. 

 It is well known that Amphioxus obtains its food by straining off the 

 nutritive particles contained in the current of water which is taken in 

 continuously at the mouth and expelled at the atriopore. It is also well 

 known that the cilia on the gill cause this continuous current, and that in 

 some way a separation of the food-particles is effected. 



The existing explanations, however, of the manner in which these two 

 processes are effected are either very vague or only partially true and 



