238 



PLANT STUDIES 



is the low type called isogamy, the pairing gametes being 

 alike. 



TJlothrix is taken as a representative of the Conferva 

 forms, the most characteristic group of Chlorophyceaj. All 



Pig. 205 Tlnlliin \ rnnfi ril fiiinl. ,l,l),is<'0f filament, sliowiiic; lowest linlrtfast 

 cell ajdti\e \L^'(titi\c cells Lich with its single eoiisjiieiions eyiindrietil cliloro- 

 pla.st (bten in section) mclosint; a niicleny ; 7?, four cells containing numerous 

 small zoospores, the others emptied; {'. fragment of a filament showing one cell 

 (a) containing four zoosjiores, ;inof|]er zoos|)ore i?i) disjilaying four cilia at its 

 pointed end and inst having esraipcd from its cell, anntlier cell (o from ^vhicll 

 most of till" small hiciljatc gametes ha\c escaped, gametes jiairing (r/i. and the 

 resulting zVL^otcs (m : I>, hegiuning of new lilanutd from zoospore; E. feeble 

 lilanienis formed b.y the small zoospores; F, zygole growing after rest; (?, 

 zoospores jirodaced by zygote. — C'ALPwyLL, excciit F and r/. which are after 



DODEL-PORT. 



the Conferva forms, however, are not isogamous, as will he 

 illnatrated by tlie next example. 



1 0.5. Edogonium. — Tliis is a very common green alga, 

 found in fresh waters (Fig. SOU). The filaments are loi^g and 

 simple, the lowest cell acting as a holdfast, as in Uloflirix 



