ivith some Remarks on the Nature of the Spongiee Mariiiée. 385 



tory hairs on tlie surface of the gianules endowed with the spontaneous move- 

 ment which I have just described, but was not able to discover any, although 

 I employed a power of 500 diameters with a good light*." Similar granules 

 of the Chara are represented in tab. 10. in Act. Acad. Nat. Curios, vol. xiii., 

 for the purpose of illustrating Dr. Agardh's memoir " On the Anatomy and 

 Circulation of the Chara,'' " Uber die Anatomic und den Kreislauf der Cha- 

 ren." Thus do these granules afford additional analogy in their spontaneous 

 movements to the sporules of the Ectosperma and of the Spongilla and Spon- 

 gia\ Since M. Donné has not succeeded in finding any cilia on the moving 

 granules of the Chara hispida, and I have before shown that the sporules of 

 the Spongilla Jiuviat'ilis are entirely devoid of them, though whether they 

 exist on those of the Ectosperma clavata 1 am not aware, but I apprehend 

 they do not : and most assuredly they do not, if those organs vibrate by the 

 sole aid of a muscularf apparatus, which, I conceive, will on further investi- 

 gations prove to be generally the case ; and hence the impossibility of such 

 cilia ever belonging to vegetable bodies. With this view, then, of those sin- 

 gular organs of locomotion, I have also stated the likelihood of those cur- 

 rents, which have been noticed flowing from the moving sporules of the Sea 

 Sponges, when examined under the power of 400 or 500 diameters of the best 

 microscope, turning out to be caused by some other agency than that of real 

 cilia. Such an agency, which I have before observed likely to be sufficiently 

 effective, is that constituted by the endosmosis and exosmosis of diflferent 

 fluids, according to the beautiful discoveries of M. Dutrochet. Though I 

 should remark, that the thin membranes forming the coverings or envelopes 

 of the sporules and granules of plants are quite porous enough to allow the 

 endosmose and exosmose fluids to act : but where papillae or any cilia-like tu- 

 bules exist, these, most possibly being hollow, will I think assist the action of 

 those fluids, and so increase the currents by which locomotion is supposed to 

 take place. And this agency, I conclude, will probably be found general in 



* See M. Donné on the Cause of the Circulation of the Charu, p. 153, in the Lond. and Edinb. Phil. 

 Mag. for August, 1838. 



+ Dr. A. Farre mentions "muscular lobes" as being present in the gemmules of the Alcyonium 

 gelatinosmn, which are endowed with true cilia. 



3 E 2 



