SEAWEEDS AND THEIR ALLIES, i ^ 1 J , 



VAUCHERIA. V. sessilis, Yauch: ' ' 

 General Characters. 



Examine with a good hand lens the specimens that 

 have been gathered, some from fresh water, others from 

 moist soil in greenhouses. Notice 



I. The coarsely filamentous appearance, and the matting 

 together to form a thick felt, when growing on the soil in 

 flower-pots. 



II. The color. Compare with the bright green of some 

 of the finely filamentous sorts growing in water. 



Microscopic Structure. 



Mount some of the filaments and examine with the 

 compound microscope. Observe 



I. The very large size of the cells, a filament, as a rule, 

 consisting of a single cell. Try to find the end of one. 

 Ascertain whether branches are formed. 



II. The thick cell-wall. Run two per cent salt solution 

 under the cover glass, and see if the wall becomes more 

 plainly defined. 



III. The cell-contents. These present considerable dif- 

 ferences, depending on the age of the plant, and the con- 

 ditions under which it grew. Good specimens show in 

 the thicker protoplasm next to the cell- wall 



1. Chlorophyll bodies. Observe their shape. 



2. Drops of oil. Apply iodine solution, and determine 



whether starch also is present. 



3. Nuclei. These require special treatment to be brought 



out satisfactorily. 1 



1 Cf. Bower and Vines, Practical Botany, II, p. 76. 



