FUNCTION.] CHARA. CONFERVAS. 145 



The same opinion was entertained by Dutrochet as to the 

 cause of the singular motion of green granules within the 

 cells of Charads. But their author eventually abandoned 

 the hypothesis. 



He submitted a Chara to the influence of a large electro- 

 magnet, capable of supporting a weight of about 4000 pounds. 

 The stem of the plant was placed a little in front of a plane 

 passing vertically through the poles of the horse-shoe magnet, 

 but quite within the magnetic influence. Careful observation 

 at the moment of establishing the electric current in the 

 coil, proved that the speed of the circulation was unaltered. 

 Left thus for ten minutes, all remained as before no influence 

 was manifested. The electric current was then suddenly 

 reversed : the circulation exhibited no alteration. The stem 

 was then exposed to the influence of each of the poles 

 separately, from the base of the stem to the apex ; still no 

 change in the circulation was visible. After each experiment 

 all magnetic influence was suppressed, but no change in the 

 rate of the motion became evident. 



It was thus shown by Dutrochet that the magnetic force, 

 even when prodigious, exerts no influence on the circulation 

 of Chara. Therefore he concluded that there could not 

 be any relation between the magnetic force and the vital 

 force producing this circulation. On the contrary, he finally 

 admitted that the circulation is caused by a vital force, which 

 is not electrical, since electricity merely acts like any other 

 exciting cause, and which has no relation to the magnetic 

 force, since the latter has not the slightest influence upon it; 

 and he fully recognised the presence of a vital force, sui generis, 

 of the nature, relations, and mechanism of which we are 

 totally ignorant. (Annals of Natural History, xvii. 450.) 



In some Confervas an active voluntary motion takes place 

 among the spores in the interior of the cells; the spores 

 strike themselves constantly against a thin part of a cell wall 

 till, by perseverance, they rupture it and escape into the 

 surrounding water. When there they swim about with their 

 small end foremost, (see Vegetable Kingdom, p. 14.) These 

 are phenomena which are clearly explicable upon no other 

 supposition than the existence of an inherent vital force. 



VOL. II. L 



