LECTURE XL 



VAUCHERIA is a very common plant. It may be found on the 

 surface of moist ground, on stones submerged in streams, or on 

 rocks splashed by trickling water. Some kinds also are marine. 

 It forms a mat-like growth of fibrous green filaments which are 

 tough, and rough to the touch, and are tangled together owing to 

 their branching. The colour 

 is dark green. The branch- 

 ing fibres may be several 

 centimetres in length. 



Owing to their matted' 

 state it is hard to separate a 

 portion for microscopic ex- 

 amination without injury to 

 it. Supposing we are able 

 to obtain a satisfactory speci- 

 men, it will be easy to see 

 that each fibre is tubular in 

 form, about 8o/x in diameter. 

 The fibres form many 

 branches, some of which 

 are colourless and of a 

 curiously irregular form. 

 These latter are rhizoids, 

 which fix the plant in posi- FlG - l6 - Vaucheria sessilis, a-/, x 40 



L ft onf ruari/ii'i n r\r\crs\rMr* /* fs\s\c*r\f\-r** 



tion by adhering to sand 

 particles, etc. The rest of 

 the plant has the dark green 

 colour. The whole plant is 

 covered by a continuous 

 membrane. It is of cellu- 

 lose and is spoken of as a 

 cell-wall. It has the usual characteristics of this substance, 

 but is rather thicker than the cell-walls of the plants which we 

 have hitherto examined. The green coloration is located in a 

 layer of material lying against the inside of this branching 



83 6* 



a, antheridia ; b, oogonia; c, zoospore; 

 d, partition cutting off zoosporangium 

 from the rest of coenocyte ; e, rhizoids ; 

 f, growing tip of coenocyte; g-m, 

 above, optical section of coenocyte, 

 x 300. g, cell-wall; h, vacuole; k, 

 layer of cytoplasm; /, chloroplasts ; 

 m, oil-drops. 



