INTRODUCTION. XXXI 



applies. But the most interesting part of the memoir is, 

 the account given of some curious circumstances attending 

 the germination of some of the lower Algae, those belonging 

 to the grass-green series, (Chlorospermece, Nob., Zoosper- 

 me<e, Ag. fil.) I allude to the peculiar motion observed in 

 the spores of several plants of this group, which has given 

 rise, on the Continent, to some very startling theories, 

 which have again produced much warm, not to say angry, 

 discussion. Without entering into all that has been written 

 on the subject, which would occupy too much space for 

 our limits, I shall here transcribe M. Agardh's account of 

 Conferva area, translating from his memoir above noticed. 

 " The filaments of C. aerea are, as is well known, articu- 

 lated or divided at equal distances into little compartments 

 (joints), which have no communication among themselves 

 other than what results from the permeability of the dis- 

 sepiments. The green matter contained in these joints 

 appears at first altogether homogeneous, as if it were fluid ; 

 but in a more advanced state it becomes more and more 

 granular. The granules are, at their formation, found ad- 

 hering to the inner surface of the membrane, but they soon 

 detach themselves, and the irregular figure which they 

 present at first passes to that of a sphere. These granules 

 congregate by degrees in the middle of the joint, into a 

 mass, at first elliptical, but which at length becomes per- 

 fectly spherical. All these changes are conformable to 

 phenomena known in vegetable life ; those which are to 

 follow have more analogy with the phenomena of animal 

 life. At this stage an important metamorphosis exhibits 

 itself, by a motion of swarming (un mouvement de fourmille- 

 ment) in the green matter. The granules of which it is 

 composed detach themselves from the mass, one after ano- 

 ther, and having thus become free, they move about in the 

 vacant space of the joint with an extreme rapidity. At the 



