OR KEN ALCxAE 



and with no distinction of apex and base. Tlicy are slimy to the 

 touch, owing to their niucilacrinoiis outer wall. Each fihimcnt is 

 partitioned by transverse septa into cells, each of which may be 

 detached from its neighbours by slmck, when its convex ends demon- 

 strate its internal turgor. Growing ou and dividing, each may form 



— i 



Fig. 337. 

 Two filaments of Spirogyra, which illustrate various slaj;is ui t, b. 



have formed outgrowths which have met ate; the protoplast </ 10 a 



dense sphere. The next lower pair of cells show ronjugati'i ; Ij*!* 



fusing at/. In ^.conjugation is complete, a zygote havinK b«<ii I'liiud bv ihc 

 fusion of two protoplasts. (.'Vfter Kny.) 



a new filament. Each cell is practically an individual (Fig. 7,^y^ cell h). 

 It is cylindrical, the proportion of length to breadth var^'ing in 

 different species. Within the external wall is a layer of coloiirlcis 

 cytoplasm surrounding a central vacuole, in the middle of which the 

 single nucleus is suspended by colourless threads. The most marked 

 feature is the green spiral chromatophore, which gives the gcnii^ 

 its name. One or more of these, according to species, may lie embcdde<l 



