﻿324 CONTRIBUTIONS TO THE NATURAL HISTORY 



the wind. Again, the undulations of the different rows are independent ; sometimes 

 all the rows playing at the same time, at other times parts of the rows, or parts of 

 each row, or parts of some rows, playing independently. 



I have been unable to ascertain what is the structure of the fringes themselves. 

 They seem to be stiff, and nevertheless they are too soft to be gathered for chemical 

 analysis. They must be decidedly of a peculiar tissue, for their appearance is quite 

 peculiar, and does not resemble that of the other tissues. The number of teeth or 

 fringes in one of the larger combs may be about fifty, but they are not equally nu- 

 merous through all the combs in one vertical row. The combs in the upper parts and 

 in the lower parts of each row, nearer the mouth and the area opposite, are gradually 

 shorter and shorter, and contain fewer and shorter fringes, the largest being about 

 the middle of the vertical height. They terminate rather abruptly above, and at a 

 greater distance from the centre than below, where they are naturally prolonged to- 

 wards the central eye-speck ; if the black tubercle in the centre of the circumscribed 

 area opposite the mouth is really to be considered as an eye-speck. 



The movements of these fringes seem at first to be identical with those of vibrating 

 cilia ; and one might be tempted to suppose that these locomotive fringes are formed 

 by a row of compressed vibrating cells, arranged in such a manner as to bring their 

 cilia in one row, and the cells themselves in such superposition above each other as to 

 form vertical series. But the cilia or fringes are far larger than any vibrating cilia ever 

 described, and their motion shows distinctly that they are under the voluntary control 

 of the animal ; for their movements are neither incessant nor constantly equal. They 

 are at times accelerated or retarded, entirely stopped and resumed at shorter or longer 

 intervals ; so that the evidence of their voluntary movement is as full as can be, and, 

 indeed, the structure which determines the movements is the same as in all cases of vol- 

 untary motion. A regular muscular apparatus can be traced along the base of each 

 comb, muscular fibres forming a regular row above and below the base of the fringes, by 

 the repeated contractions of which the fringes are moved up and down like flappers, in 

 quick succession. But notwithstanding this muscular apparatus, which may be com- 

 pared to a pennate muscle, the axis of which would constitute the point of insertion 

 of the fringes, and thus control their movements up and down, it is hardly possible to 

 refrain from the idea that these fringes are, after all, in some way or other, connected 

 with vibratory cilia, — that they are vibratory cilia on a gigantic scale. And I do not 

 see why there should be nowhere in the animal kingdom a transition between a par- 

 ticular arrangement of muscles moving independent appendages, and the structure 

 of a ciliated cell regulating the motions of its own vibrating fringes. And if this 



