378 Mr. Hogg's Observations on the Spongilla fluviatilis, 



Professor Don, by whose kind assistance I was enabled to see these bodies 

 magnified 400 times : even at such a high power we both were unable to 

 discern the presence of any cilia, but most distinctly observed the entire 

 covering or membrane of the sporules to be 'Studded all over with short pa- 

 pillae. Now it is very probable that the currents in the water, which I sup- 

 posed to have been caused by the rapid vibrations of tufts of cilia, were cur- 

 rents produced by a reciprocal action, or, to use the terms of M. Dutrochet, 

 by an endosmosis and exosmosis, /. e. by an inward and an outward impul- 

 sion of fluids, not only through the membranes of these sporules, but also 

 through these mend^ranaceous papilke, in accordance with the discoveries of 

 that distinguished physiologist. Wherefore, the currents so produced would 

 I conceive be a satisfactory mode of accounting for the singular and beautiful 

 phenomenon of locomotion as exhibited in these sporules ; and it is in pur- 

 suance of the philosophical views of Mr. Berkeley, F.L.S., as briefly mentioned 

 by him in a paper " On the supposed Animal Nature of the Seeds of certain 

 Algcv^' pidjlished at p. 233 of Hooker's Journal of Botany, part 3, for July 

 1834* ; although, if this hypothesis should ultimately not prove the correct one, 

 we must endeavour at another opportunity to investigate the causes of that 

 interesting phenomenon by a more minute and complete examination of the pa- 

 pilUe with which those sporules are so abundantly furnished, and whilst they 

 are in a fresh state ; for indeed I cannot but imagine that the function of loco- 

 motion must be in part carried on by means of the currents which I noticed in the 

 water, proceeding from the sporules, and very possibly effected in some degree 

 by a peculiar, but as yet unknown, faculty of the papillae themselves. 



Hence, from what has been said, it will be evident that locomotion being- 

 common both to some bodies pertaining to plants, and also to animals, the 



* I think it better to insert here from that work Mr. Berkeley's own explanation of what he thinks 

 the real case to be : " When the seed separates from the matrix, it passes into the water in which the 

 plant is immersed. Now if the contents of the seed, which are semifluid, are of a different specific 

 gravity from that of water, a mutual action of exosmose and endosmose will immediately take place 

 through the epidermis of the seed : the water will pass into the seed, and part of the fluid matter of 

 the seed will pass out into the water ; and in consequence of this action, the current produced will 

 cause the seed to move about, until an equilibrium take place, when the seeds will settle at the bottom 

 and begin to vegetate." See, for additional remarks on the same subject, p. 28 of Berkeley's " Glean- 

 in:;s of British Algse," Lond. 1833, where in plate x. the Ectosperma clavata is well represented. 



