INTRODUCTION. 15 



red, which adds still further to their resemblance to certain 

 Infusoria, especially to some Thecamonadiens. 



The Chcetophora elegans (var. pisiformis) presents to us 

 a more complicated organization. The beak bears four loco- 

 motive tentacles, instead of two. These spores are very small 

 also, and difficult to observe. (See Plate I. Jiff.- 10.) 



In the ProlifercB ( Conferva vesicata, tumidula 9 smd alternata), 

 the organization is still more complicated ; and this difference 

 of the spores is an additional motive for separating these plants 

 from the real Conferva. Two species of this kind have served 

 me in my researches : the first seems to be referrible to Pro- 

 lifera rivularis of M. Leon Le Clerc* ; and the other, a great 

 deal smaller in all its parts, to Prolifera Candollii of the same 

 author. Both have the spores, the beak is rounded, and bears 

 a crown of filiform tentacles (see Plate I. Jiff. 13. 18.), which 

 opium or iodine renders motionless. Their movements are 

 very nearly the same as those of the spores of the Conferva, 

 but much more rapid, by reason of the greater powers of their 

 locomotive organs. When these spores are disposed to ger- 

 minate, they fix themselves by the beak to all tendrils which 

 float in the water, and throw out prolongations or root-like 

 claws, which render them very adherent. The filaments of 

 Prolifera., or Conferva., are often rendered rough with this 

 kind of parasitic vegetation. This fact, ill understood, caused 

 the creation, by Yaucher, of the erroneous appellation of Pro- 

 lifera. If the plant is removed from the water at the 

 moment of the emission of the spores, they fix themselves 

 around the crystals produced by the evaporation of the liquid ; 

 and when the germination commences, one may see every 

 little crystal charged with a multitude of spores which 

 radiate in all directions. 



The Vaucheria, estranged from the genera of which we 

 have been speaking, by its structure, and by the mode of the 

 formation of its spores, is distinguished equally by the dis- 

 position of its locomotive organs. The spore is an ovoid 



* Sur la Fructification du Genre Prolifere. (Memoires <lu Museum, 

 torn. iii. p. 462. pi. 23.) 



