CILIA. 625 



oscillatory motion was communicated by the wards on one side, and then in an eddying 



agitation of the globules underneath it. He manner back again." 



perceived the motion in question in no part Raspail, in a memoir on a species of fresh- 

 but the labial appendages, and he imagined it water polype, published in 1828,* pointed out 

 to be connected with the male generative func- the analogy between the phenomena exhibited 

 tion, of which he therefore conceived the parts by the gills of Mollusca and those observed in 

 mentioned to be the organs. It is obvious that infusory animalcules and polypi, 

 the appearance seen by Ehrman was the undu- Ciliary currents were now described by vari- 

 lating motion of the cilia, which organs, how- cms other writers of eminence, but their causes 

 ever, he had not recognised. He makes no were very commonly mistaken: among the 

 mention of currents, and consequently could number may be quoted Poli,f Delle Chiaje,J 

 not perceive the connexion of the phenomenon Carus, De Blainville,|| and Unger.^f 

 with respiration, which was also less likely to Having observed currents produced in other 

 occur to him, as he supposed the motion to be instances by an impelling power inherent in 

 confined to the appendages mentioned. the surfaces over which the fluid passed, I was 



The observations of Ehrman led Treviranus myself led to suspect that the respiratory cur- 



to investigate the subject;* and he distin- rent in bivalve Mollusca was of the same kind, 



guished two different motions, the one a mus- or that it was caused by an impulsion commu- 



cular contraction, the other the peculiar motion nicated to the water by the surface of the gills 



alluded to by Ehrman. The latter motion had and other parts over which it was conveyed in 



the appearance of a trembling or flickering its passage, without being aware of any similar 



of innumerable points, and seemed at some view having been entertained by others. I 



places as if produced by a moving fluid, and then observed the determinate direction of the 



at others by the agitation of oblong vibrating impulsion along the surface, together with the 



organs. It was peculiarly distinct alongside arrangement and action of the cilia. These 



each of the bars of the gills and appendages, observations were published at the time (1830) 



He farther perceived that the agitation on the in a paper already mentioned,** in which also 



surface of these parts caused an eddying mo- the respiratory currents of the bivalve Mollusca 



tion in the water in which they lay, and also are considered as a particular example of a 



set in motion globules of blood which had more generally prevailing phenomenon, 



escaped from the vessels. On breaking down In a paper on the circulation of the blood, 



the parts into small fragments, he found that in Magendie's Journal for 1831, ft there are 



each retained its power of motion, by which some remarks pertaining to the present subject, 



they moved in most manifold directions, the from which it appears that the author, M. 



larger masses at the same time contracting and Guillot, had observed the ciliary motion of the 



dilating themselves. From these observations gills of the Sea-mussel and Oyster. He has, 



Treviranus concludes that the bivalve Mollusca however, like Baker, mistaken the regular un- 



afford an example of a structure in which the dulations of the cilia for the circulation of a 



integrant parts possess an independent vitality, fluid within vessels. He takes no notice of 



Their independent vitality shews itself in the any motion or current excited in the water, 



persistence of their automatic motion after Carus,JJ in a memoir on the development of 



solution of organic connexion with each other, the River-mussel, states that he observed an 



and this motion is intermediate in its nature undulatory or oscillatory motion of the gills, 



between the spontaneous movements of organic and that by this motion, which he conceives to 



molecules in infusions, the male semen, &c. be in the substance of the gill, the water is 



and the motion of muscular parts, which re- propelled, and the general respiratory current 



quires the integrity of the texture and the through the branchial cavity produced. It is 



application of a stimulus. These reflections obvious that what he calls an oscillation of the 



on the relation of the phenomenon to the substance of the gill, and which he erroneously 



general laws of organization are the sole infe- supposes has previously escaped attention, is 



rences which he draws from his observations, merely the undulatory motion of the cilia. 



He notices the motion of the water only as a The last researches on this subject which we 



concomitant and subordinate circumstance, not have to notice are those of Purkinje and Va- 



having been aware of its determinate direction, lentin. As above stated, they discovered the 



its relation to the respiratory process, or, in ciliary motion in the alimentary canal of the 



short, of its being the chief end and effect of Mollusca, having found it in the Lymnsoa, Pa- 



the motion of the cilia. ludina, and the Fresh-water mussel. 



The next researches on the subject are those 

 of Huschke, narrated in a paper in the Isis for 



1826.f Not having seen the original, we must ' M emoires de la Soc. d'Hist. Nat. de Paris, 



content ourselves with a brief notice of them to t | 6 - W * P> 131 ' seq> :himie Or g ani( l ue > 1833 > 



be found in Burdach's Physiologic.} It is there % Testacea utriusque Siciliae, t. i. 51. 



stated that on detaching a portion of the gill J Istituz. diNotom. e Fisiolog. comp. t. i. p. 278. 



of the Fresh-water Mussel (Unio pictorum), ,Lehrbuch der Zootomie. 



Huschke found that the water " moved up- [ Malacologie, 157. 



I Uber die Teichmuschel, p. 10. 

 ** Edin. Med. and Surg. Journal, vol. xxxiv. 



Vermischte Schriften, Band iii. p. 234. ft Tom. xi. p. 182. 



t P. 623. jj Nova Acta Acad. Caes. Loop. xvi. p. 58, seq. 



f Band iv. p. 434. Loc. cit. 



