Mucus-substance of the Cell in the Characese. 123 



within a rigid ligneous membrane, which permits only an in- 

 ternal motion, evidenced in the phsenomena of circulation and 

 rotation ; while in the former it is not thus enclosed. The pro- 

 toplasm in the form of the primordial sac is, as it were, the ani- 

 mal element in the plant in which it is confined, being /ree only 

 in the animal kingdom/^ 



Casual Notes on the Characese. 



Circulation. — I have repeated the experiments of Amici, Du- 

 trochet and others by ligaturing the internode of the large Nitella 

 at several places with similar results. The circulation has hardly 

 been arrested ; but to succeed well in this, an old internode must 

 be taken. On one occasion an inch of one of these long inter- 

 nodes was cut out of the centre with a blunt pair of scissors and 

 placed on a glass slide in a little water, and under a piece of 

 glass about the same width ; the water therefore but just covered 

 its extremities ; in this portion the circulation continued in op- 

 posite directions (for fortunately one of the white lines or 'Hines 

 of repose ^' was uppermost) for ten minutes by the watch ; the 

 larger bodies ceasing to circulate first, and lastly the molecules. 



Tenacity of life. — The internodes which I ligatured perished 

 after a few days ; indeed this is the common fate of the Cha- 

 racese ; but the nodes retain their vitality, and the small inter- 

 nodes also. Single, isolated cells and small internodes, which 

 can hardly be seen with the naked eye, frequently retain their 

 green colour, and keep up a continued rotation of their mucus- 

 layer for eight and ten months after they have been separated 

 from every part, dead and living, belonging to the parent plant ; 

 but they do not appear to increase in size in the least. Those 

 little shoots which spring from the cells of the nodes (the bulbels 

 probably of Montague*) would probably grow into new plants 

 if favourably situated for nourishment, as the nodes commonly 

 throw out roots as well as shoots, when the other parts of 'the 

 plant are threatened with destruction. 



Endosmosis. — The rapidity with which water passes through 

 the cell-wall of the internode, as shown by the experiment de- 

 tailed at the commencement of this paper, indicates the amount 

 of fluid that might pass from one internode to another through 

 contact even of their extremities ; and hence how the nutritious 

 fluid formed in the roots might also find its way from the roots 

 to the extremities of the plant. 



Germination. — The nucules of Char a verticillata which were 

 placed in water on the 21st of March germinated at the end of 



* Ann. des Sc. Nat. Bot. 3 ser. t, xviii. p. 65. 



