Cilia / by W. Sharpey.

  • Sharpey, William, 1802-1880.
Date:
1836
Catalogue details

Licence: Public Domain Mark

Credit: Cilia / by W. Sharpey. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Ciliograde Medusa? afford a good example. In these, in place of cilia of the usual form and arrangement, there are rows of broad flattened organs, each of which is made up of several simple filaments joined together by a common base, according to Eschscholz, or according to Dr. Grant by a connecting membrane in their whole length. The entire organ is raised or depressed at once, so that the filaments are all moved simultaneously, like the eye-lashes. The compound cilia in some of the Rotatoria, de- scribed by Ehrenberg, are probably of the same nature. 5. Of the appearance of the cilia in motion. —On examining these organs with a lens of ^ inch focus, when their motion is not very rapid, the manner in which the individual cilia move may be distinguished with tolerable cer- tainty. Most commonly they have a fanning or lashing motion, that is, the cilium is bent in one direction and returns again to its original state. The flexion takes place chiefly at the base or root, but not wholly there, for the rest of the organ is obviously bent and altered in figure; nay, the more elastic cilia, when their motion abates in intensity, appear some- times to bend only near the point, the base and adjoining part remaining motionless. When a number of cilia are affected in suc- cession with this motion, the appearance of a progressive wave is produced, and as in such a case they are again and again moved in the same way at very short intervals, successive waves proceed along them in the same direc- tion, which might be compared to those pro- duced by the wind in a corn-field. Such at least seems to be the true explanation of the undulatory motion which so often occurs, although it must be confessed that the motion of the cilia individually cannot be distinctly seen when the undulation is most perfect. The undulations succeed one another along a range of cilia with great regularity, and except in the Rotifera, and perhaps some other Infusoria, they seem always to maintain the same direction in the same parts. Purkinje and Valentin describe the motion of the individual cilia as being more frequently rotatory, or, as they term it, infundibuliform; and Ehrenberg states this to be the common mode in the Infusoria; the cilium describing a circle with its point, while the base is the centre of motion. Erom my own observation, how- ever, I would be inclined to infer that this motion is by no means the most common. 6. Duration of the cilian/ motion after death and in separated parts.—The continuance of the ciliary motion for some time after death, and the perfect regularity with which it goes on in parts separated from the rest of the body, are facts which have been already repeatedly stated, and sufficiently prove that the motion is quite independent of the will of the animal, and also that it is not immediately influenced by the circulation of the blood, even in the respiratory organs. The time which it continues after death differs in different species of animals, and also, but in a much smaller degree, in different parts of the same animal. Its duration is influenced also by the temperature of the air, and by the nature of the fluid in contact with the surface. In Mammalia and Birds the period varies from half an hour to four hours, being longer in summer than in winter; but it is still further prolonged when the parts are covered with blood. In the gills of Batrachian larva; I have seen the motion continue six hours; but of all vertebrated animals it is most enduring in the Tortoise, in which animal Purkinje and Valen- tin affirm they observed it fifteen days after death, when putrefaction was far advanced; the irritability of the muscles remained in the same animal for seven days. Among the in- vertebrata the River-mussel affords an instance of the great pertinacity of the motion, which ceases only when putrefaction has advanced so far as actually to destroy and dissolve the tissues. 7. Effects of external agents on the ciliary motion. — Steinbuch, Purkinje, and Valentin allege that on touching the parts, or giving them a gentle shock by merely striking against the object plate of the microscope, the motion is rendered brisker when it has become languid, or is even renewed in parts where it has ceased. They, however, attribute more importance to this fact than it seems to deserve ; for it may be doubted whether the concussion in renewing the vivacity of the cilia does not act merely by removing obstacles which impede their play. Electricity and galvanism produce no visible effect. A powerful discharge from a Leyden jar was made to pass through the River-mussel by Purkinje and Valentin without causing any change in the ciliary motion. Portions of the external gills of the Tadpole were subjected by myself to the same experiment and with a similar result, except when the surface was abraded, which occasionally happened with a strong discharge. 1 have exposed portions of the gill of the River-mussel while viewed with the microscope, to the influence of a galvanic battery of twenty-five pairs of three-inch square plates, charged with solution of salt, without being able to perceive the slightest effect on the motion of the cilia. The authors above men- tioned obtained a similar result, both in the Mussel and the domestic Fowl. The effect of temperature is different in warm and cold-blooded animals. In the former, ac- cording to Purkinje and Valentin, the motion stopped on exposure to a temperature of 43° F. while it went on at 54° E. On the other hand they found that in the Fresh-water Mussel it was not affected at 32° F.; and I found the same to be true of the Tadpole. A portion of the gills of the River-mussel, which I kept for five minutes in water at 96° F. shewed no change. Acids, saline solutions, and other substances applied to the parts, differ in their effects ac- cording to the kind of animals submitted to experiment. Thus, for example, fresh water instantly arrests the motion in the Marine Mol- lusca, and also in other marine animals in which I have tried its effect, though a satu- rated solution of sea-salt destroys it both in salt and fiesh-water species. Purkinje and