Abstract
IT is well known that the embryo of the frog exhibits remarkable movements of rotation, the direction being in opposition to that of the movements of the hands of a watch, supposing the observer to be looking vertically down upon the instrument, and that the head of the animal is directed away from him. These movements continue without interruption, and may be watched for hours together. They vary considerably in rapidity, but a series of observations made by Dr. Schenk showed that the rotation was effected in from five minutes and thirteen seconds to twelve minutes and two seconds. It has not been accurately ascertained when these movements commence, since in the earliest stages of development the surface of the egg is in close contact with the capsule, and it is only after some water has been imbibed that the two are separated, but Dr. Schenk shows that they result from the presence of ciliated cells on the surface; first, because these can be demonstrated with the microscope; secondly, because they can be accelerated by the application of moderate heat, which is well known to render the movements of cilia more rapid, and thirdly, because they can be arrested almost instantaneously by the action of weak acids, which are known to operate in the same way on ciliary movements.
On the Rotation of the Embryoes of the Frog within the Egg.
By Dr. S. L. Schenk. Pflüger's Archiv. 1870, iii. Jahr., Heft 2 and 3.
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On the Rotation of the Embryoes of the Frog within the Egg . Nature 1, 650 (1870). https://doi.org/10.1038/001650b0
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DOI: https://doi.org/10.1038/001650b0