328 



consider it near Confervae, chiefly on account of the organisation of the 

 stems ; for it does not seem that the reproductive organs of flowerless plants 

 are of the same degree of importance in deciding affinities as the fructification 

 of flowering plants. Its total want of vascular system renders it impossible 

 to adopt the opinion of those who would place it near Ferns next to 

 Marsileacese, and the regularity with which all the parts are formed round 

 a common axis renders it equally impossible to refer it absolutely to the 

 leafless section. I therefore place it on the limits of the latter, among 

 Muscoidese. 



There are two other points deserving of attention in Characeae : 1st, 

 the calcareous incrustation of some species ; and 2dly, the visible and rapid 

 motion of the sap in the articulations of the stem. 



Of the two genera, Nitella is transparent and free from all foreign matter; 

 but Chara contains, on the outside of its central tube, a thick layer of calca- 

 reous matter, which renders it opaque. This incrustation appears, from the 

 observations of Dr. Greville (Fl. Edin. 281), not to be a deposit upon the 

 outside, and of an adventitious nature, but the result of some peculiar 

 economy in the plant itself; and according to Dr. Brewster, it is analogous to 

 the siliceous deposit in Equisetum, exhibiting similar phenomena. 



Whatever is known of the motions of the fluids of vegetables has been 

 necessarily a matter of inference, rather than the result of direct observation ; 

 for who could ever actually see the sap of plants move in the vessels destined 

 to its conveyance ? It is true that it was known to botanists that a certain 

 Abbe Corti of Lucca, had, in 1774, published some remarkable observations 

 upon the circulation of fluid in some aquatic plants, and that the accuracy 

 of this statement had been confirmed by Dr. Treviranus so long ago as 1817; 

 but the fact does not seem to have attracted general attention until the pub- 

 lication, by Amici, the celebrated professor at Modena, of a memoir in the 

 18th volume of the Transactions of the Italian Socielxj,'vi\\\c\\ was succeeded 

 by another in the 19th. From all these observers it appears, that if the stems 

 of any transparent species of Chara, or of any opaque one, the incrustation 

 of which is removed, are examined with a good microscope, a distinct current 

 will be seen to take place in every tube of which the plant is composed, set- 

 ting from the base to the apex of the tubes, at the rate, in Chara vulgaris, of 

 about two lines per minute {v. Ann. des Sc. 2. 51. line 9) ; and according to 

 Treviranus this play is at any time destroyed by the application of a few drops 

 of brandy, by pressure, or by any laceration of the tube. This is the nature 

 of the singular phenomena which are to be seen in Characese, and which 

 become the more interesting because they are not to l)e found in any other 

 water-plants, with the exception of Naias and Caulinia. Those who are 

 anxious to become acquainted with the details of Amici's observations will 

 find his first paper translated in the Annales de Chiinie, 13. 384, and his 

 second in the Ann. des Sc. 2. 41 ; that of Treviranus is to be found in the 

 latter work, 10. 22. According to the last-named author, these facts lead 

 to the conclusion that there is a primitive vitality in amorphous organic mat- 

 ter, which is antecedent to the formation of all organic beings, and is in its 

 turn produced by them, to serve, according to circumstances, either for the 

 support or enlargement of the individual, or for the production of a new 

 organisation. This vitality is manifested in movements which may appear 

 to take place without rule or object, but whicli are dift'erently modified 

 according to the diflerences of organic bodies ; all which seems to shew 

 that the vital principle is oriuinally susceptible of a variety of modifica- 

 tions, without having occasion for the assistance of organs of various forms 

 pr structure. 



