INTRODUCTION. XXXV 



has found many advocates among continental writers, 

 among which we must number the elder Agardh, who 

 speaks of the disengaged spores of Tetraspora lubrica as 

 " having become animalcules ; " whilst others have strongly 

 combated it, and in England it has never been received. 

 Mr. Berkeley (' Hook. Journ. Bot.' i. p. 233), in combating 

 such notions, suggests that this motion may arise from the 

 endosmose or exosmose caused by the spores being of a 

 different density with the water into which they are dis- 

 charged ; but, as Mr. Agardh remarks, this cannot be the 

 reason, for the motion equally exists in Conf. cerea before 

 the spores are separated from the frond. He likewise de- 

 nies the animal nature of the spores, observing, " the spo- 

 rules have never any opening analogous to the mouth of 

 infusorial animals, and we never perceive them to swallow 

 any food. Their motion, however irregular and capricious 

 it may appear, however like it may be to spontaneous 

 motion, is easily distinguishable from motion truly animal, 

 although this distinction may be difficult to establish by 

 decided characters. And besides, why refuse a locomotive 

 faculty to vegetable life, when each day we discover new 

 indications of it ? The researches of M. Unger on the 

 anther of Sphagnum show analogous motions among the 

 mosses ; and the spermadic granules offer an example of 

 it among phsenogamous plants." It is scarcely necessary 

 to add that I fully unite in the view taken by this ingenious 

 writer ; that we are neither to regard the phenomenon in 

 question as caused by external agency, or as resulting from 

 an animal existence, but receive it as a strictly vegetable 

 peculiarity, which we are to expect will be observed in 

 many more instances, when our insight into the very imper- 

 fectly explored regions of vegetable anatomy shall be 

 clearer than it is. A few years ago the circulation of the 

 juices in Chara was considered extraordinary ; a similar 



