244 CHARACEJE. 



gated particles, which possessed double refraction, and had re- 

 gular and depolarizing axes." 1 



In those species of Cliara which are destitute of the calca- 

 reous incrustation, and even in those which possess it, when that 

 covering is removed, the movement of the sap has been distinctly 

 observed and brought into notice by Professor Amici of Modena. 

 Each joint or distinct tube has its own peculiar circulation, and 

 the movement was ascertained in C. vulgaris to be at the rate 

 of 2 lines per minute. M. Blainville witnessed the phenomenon 

 with Professor Amici, and observes that the microscope brought 

 to view a movement of 2 liquid currents, the one ascending and 

 the other descending, circulating in the same tube, without being 

 separated by any partition which could insulate them. The reality 

 of this was placed beyond a doubt by the distinct passage of 

 certain molecules of one of the currents, which, being attracted 

 by the one which moved in the opposite direction, were occa- 

 sionally dragged along with it. 2 



Notwithstanding the minute size of the nucules of the Genus, 

 Cliara, they occur in a fossil state both in the marie deposits in 

 the lakes of Forfarshire, and in the chalk of Montmartre, where 

 they are known by the name of Gyrogonites, and were long 

 considered by naturalists to belong to some extinct testaceous 

 animals. In the first-mentioned situations, the same species (C 

 hispidd) has been found also to exist very abundantly in a recent 

 state in the water which covers the beds of calcareous marie 

 that include the fossil nucules. 



Professor Agardh has divided the Genus into Nitella and 

 Chara, characterizing the former by its having a single, jointed 

 tube composed of a very thin colourless membrane, resembling that 

 of his Genus Valonia, the globules and nucules separated, desti- 

 tute of bracteas and with scarcely any perceptible prominences or 

 points crowning the nucules : — whilst, in Chara, the principal tube 

 is covered by several lesser tubes, (except in the part which is 

 buried in the mud and in the extremities of the branches,) the 

 globules and nucules are placed near each other, supported by many 

 bractese, and the nucules are crowned with distinct teeth. But 

 the character derived from the simple or compound stems is of 

 extremely difficult investigation, and that deduced from the 

 situation of the organs of reproduction does not appear to 

 be constant. 



Species of Chara, scarcely differing from those of Europe, 

 I have received from almost every part of the world ; from Ice- 

 land in the north (where they sometimes grow in the hot 

 springs) to the tropics, and in both hemispheres. They are 

 found carpetting the bottoms of ditches, and stagnant waters, and 

 frequently yielding a very disagreeable odour. Trout and Carp 



1 Ed. Phil. Journ. v. 9. p. 194. 2 Brewster's Ed. Journ. 1827, p. 384. , 



