CILIA. 



635 



Valentin state the effects which they found to 

 result from the application of various sub- 

 stances, but erroneously conceiving, from some 

 preliminary trials, that the same substance 

 produced the same effect in all animals, they 

 confined their experiments to the Fresh-water 

 Mussel. According to their experiments,which 

 were made with a great many different sub- 

 stances, most of the common acid, alkaline, 

 and saline solutions, when concentrated, arrest 

 the motion instantaneously; dilution, to a 

 degree varying in different substances, pre- 

 vents this effect altogether, and a less degree 

 of dilution delays it. The same is the case 

 with alcohol, aether, aqua laurocerasi, sugar, 

 and empyreumatic oil. Kreosote, muriate of 

 baryta, sulphate of quinine, infusio pyrethri, 

 and muriate of veratria, act less intensely. Hy- 

 drocyanic acid and watery solutions or in- 

 fusions of belladonna, opium, capsicum, ca- 

 techu, aloes, musk, gum-arabic, acetate of 

 morphia, and nitrate of strychnia, produce no 

 effect whatever. They accordingly infer that 

 the substances affect the motion only in so far 

 as they act chemically on the tissue. 



The result of my own experiments differs 

 from theirs in some points. In the River-mus- 

 sel I found that hydrocyanic acid, containing 

 ten per cent, of pure acid, invariably destroyed 

 the motion. Solution of muriate of morphia, 

 of medicinal strength, also arrested the motion 

 in the Mussel, but not in the Batrachian larvae. 

 The motion on the gills of these larvae also 

 continues unimpaired in water deprived of air 

 by boiling, or distilled, or impregnated with 

 carbonic acid; a sufficient proof, it may be 

 remarked, that it is independent of the che- 

 mical process of respiration. 



In regard to the effect of animal fluids, the 

 authors already mentioned state that bile ar- 

 rests the motion, while blood has the property 

 of preserving it much beyond the time that it 

 lasts in other circumstances, at least in verte- 

 brated animals ; thus it continued three days 

 in a portion of the windpipe of the Rabbit, 

 which had been kept in blood. But it is sin- 

 gular that blood or serum, whether of Quadru- 

 peds, Birds, or Reptiles, has quite the opposite 

 effect on the cilia of invertebrated animals, 

 arresting their motion almost instantaneously. 

 Albumen and milk also possess the conserva- 

 tive property, though in a less degree. 



8. Effects of' inflammation. Purkinje and 

 Valentin excited inflammation artificially in 

 the nose and vagina of rabbits, and are in- 

 clined to conclude from their experiments, 

 which however are not numerous, that inflam- 

 mation arrests the motion. 



9. Of the power by which the cilia are 

 moved. It may next be inquired by what 

 means or by what power the cilia are moved ; 

 and, in particular, whether their motion, like 

 other visible movements in the animal body, 

 is effected by muscular action. 



Dr. Grant,* reflecting that in the Beroe a 

 vessel conveying water runs beneath each row 



* Trans, of Zoological Society of London, 

 vol. i. p. 11. 



of cilia, and that, according to M. Audouin, 

 in an allied genus of animals the water enters 

 the cilia, is disposed to liken the motion of 

 the cilia to that of the feet of the Echinoder- 

 mata. He seems accordingly to think it pro- 

 bable that the cilia are tubular organs, which 

 are distended and protruded by the injection 

 of water into them from elastic tubes running 

 along their base, in which the water is conveyed 

 by successive undulations. 



This view, however, seems scarcely recon- 

 cilable with the fact that the motion of the 

 cilia continues in parts separated from their 

 connexion with the rest of the body, portions 

 so small that not more than two or three cilia 

 are attached to them, and in which the ope- 

 ration of the supposed undulating tubes can 

 scarcely be conceived. 



Ehrenberg states that in the Infusoria he 

 observed that the cilia were bulbous at the 

 root, and that they were moved by small mus- 

 cles attached to the bulb. Purkinje and Va- 

 lentin also admit the existence of a bulb, and 

 they conceive it likely that the cilia are moved 

 either by muscular substance placed within 

 the bulb, or by certain fibres which they be- 

 lieve they have discovered in the adjacent 

 tissue. They describe these fibres as existing 

 in the substance of the membranes or other 

 parts supporting the cilia, being situated at 

 the surface, straight and parallel, and ap- 

 pearing to be connected together by delicate 

 cellular tissue ; and they think it highly pro- 

 bable that they are of a muscular nature. 



The whole phenomena of the ciliary motion 

 seem to me most consistent with the notion 

 that it is produced by muscular action. I 

 must confess, however, that I have never seen 

 the muscular fibres described, nor the bulbs ; 

 and perhaps the cilia are not moved merely 

 by muscular fibres attached to their base, like 

 the whiskers of the seal and cat, but may con- 

 tain muscular substance throughout a greater 

 or less portion of their length, by which they 

 can be bent and extended; or perhaps they 

 may in some instances be bent by muscular 

 fibres, and resume their original shape and 

 position by virtue of their elasticity. 



We need not hesitate to admit that the 

 ciliary motion is the result of muscular action 

 on account of the smallness of the muscular 

 apparatus necessary ; for the researches of 

 Ehrenberg on the Infusoria have brought to 

 light examples of complex organization on as 

 minute a scale as any here required. Nor 

 need we hesitate on account of the great ra- 

 pidity of action; for there are familiar instances 

 of muscular motions of equal velocity. The 

 continuance of the ciliary motion after death 

 and in parts detached from the rest of the 

 body, and its regularity in these circumstances, 

 are appearances, startling at first, but which, 

 though they differ in degree, may be fairly 

 compared with those produced in similar cir- 

 cumstances by involuntary muscular action, 

 and may be attributed to the same cause. 

 Thus the different parts of the heart, which 

 during life contract in a certain order inde- 

 pendently of the will, continue to act in the 

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