28 



CHARACEjE. 



[Algals. 

 (A nn. Sc. N. 2 ser. 



brown by iodine and not dissolved by ammonia as animalcules are. 



U 6fi ) They arc probably analogous to the clastic spirts of Equiseiuu.. 



Thc'-c are two other Points deserving of attention in Charas ; 1st, the calcareous 

 incrustation of some species; and 2dly, the visible and rapid motion of the sap in the 

 articulation of the stem. . -_ 



Of the eenera, Nitella is transparent and free from all foreign matter; but Chara 

 contains, on the outside of its central tube, a thick layer of calcareous .matter .which 

 renders it opaque. This incrustation appears, from the observations of Greville (Fl. 

 Edin. 281), not to be a deposit upon the outside, and of an adventitious nature, but a 

 result of some peculiar economy in the plant itself; and according to Brewster, it is 



anal us to the siliceous deposit in Equisetum, exhibitmg 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 couid ever 



actually see the sap of plants move in the vessels destined 

 to its conveyance \ It is time 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 acciu-acy of this state- 

 ment had been confirmed by Treviranus so long ago as 

 1817; but the fact does not seem to have attracted general 

 attention until the publication, by Amici, the celebrated 

 professor at Modena, of a memoir in the 18th volume of 

 the Transactions of the Italian Society, which 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 hi every tube of which the plant 

 is composed, setting from the base to the apex of the tubes, 

 and returning at the rate, in Chara vulgaris, of about two 

 lines per minute (v. Ann. clcs Sc. 2. 51. fine 9) ; and accord- 

 ing to Treviranus this play is at any time destroyed by the 

 application of a few drops of spirit, by pressure, or by any 

 laceration of the tube. Such is the nature of the singular 

 phenomena that are to be seen in Charas. Those who 

 are anxious to become acquainted with the details of 

 Arnica's observations will find his first paper translated hi 

 the Annates tie Chimie, 13. 384, and Ids second in the 

 Ann. clcs Sc. 2. 41 ; that of Treviranus is to be found in 

 the latter work, 10. 22. The observations made upon 

 by the foregoing authors have been much extended by the careful 

 Solly, Slack, and Yaxley, whose remarks are to be found in the Trans- 

 actions of the Society of Arts, vol. 49, p. 177, and vol. 50, p. 171 ; and by Donne, 

 Dutrochet, and others, in the Am,. Sc. Nat. 2 ser. vol. 9, pp. 5, 65, 80, and \0,p. 346. 

 As however they relate to physiological and not to systematical questions I forbear to 

 dwell upon them in this place. 



The creation of plants of this order would appear to have been of a very recent date, 

 compared with that of Ferns and Palms, or even Algals, if we are to judge by their 

 fossil remain-, called Gyrogonites, which are found for the first time in the lower fresh- 

 water formation, along with numerous Dicotyledonous plants resembling those of our 

 own sera. In the recent Flora of the world they make their appeal ance everywhere 

 in stagnant waters, in Europe, Asia, and Africa, in North and South America, in New 

 Holland, and in either In. lia. They are most common in temperate countries. 



We can scarcely claim any knowledge of their uses. Their stems, often encrusted 

 with lime in the state of carbonate according to some, and of the phosphate according 

 to others, are probably useful as a manure. The fetid effluvium arising from them is 

 n u aided as vers unhealthy, and one of the sources of the malaria of the Campagna of 

 Rome. 



GENERA. 

 Chara, /. Nitella..!/. Charopsis, Kilts. 



Numbers. Gen. 3. Sp. 35. 



Fig. XII. 



Chara circulation 

 inquiries of 



Position. — Ceramiacese. 



Fluvial s. 



Ciiarace.e. - 



Equist i" i . 



i Ml.*- A magnified view of Nitella, with the motion of its sap shown by arrows. 



