154 



MOFPIWLOG V. 



and other plants, and has been foimd quite abundantly for sev- 

 eral )'ears in the waters of Cayuga Lake at its southern extremity. 

 As will be seen it consists of a single layer of green cells which 

 radiate from the center in branched rows to the outside, the cells 

 lying so close together as to form a continuous plate. The plant 

 started its growtli from a single cell at the central jjoint, and grew 

 at the margin in all directions. Sometimes they are c|uite irregu- 

 lar in outline, when they lie quite closely side bv side and inter- 

 fere with one another by pressure. If the surface is examined 

 carefiillv there will be foimd long hairs, the base of which is en- 

 closed in a narrow sheath. It is from this character that the 

 genus takes its name of coleocha^te (sheathed hair). 



324. Fruiting stage of coleochsete. — It is possible at some 

 seasons of the year to find rounded masses of cells situated near 

 the margin of this green disk. These ha\-e de\elopjed from a 

 fertilized egg «'hicli remained attached to the ]}lant, and prob- 

 ably by this time the parei'.t plant has lost its <olor. 



325. Zoospore stage. — This mass of tissue does not de\-elop 

 directly into the cir(ailar green disk, but each of the cells forms 

 a zoospore. Here then, as 

 in cedogonium, we have an- 

 other stage of the ]ilant in- 

 terpolated between the ler- 

 tilized egg and that stage 

 of the plant which bears the 

 gametes. Rut in coleochrete 

 we have a distinct aihance in 

 this stage upon what is pres- Y\g 157. 

 ent in cedogonium, tor in, Puriion of thaiius of Co- 



leoclia'te scutata, showing 



coleochrete the fertilized '"'P'y ."Hs from which 



zoogonidia have escaped, 



egg develoilS filSt into a °ri,e 'mm each cell ; zooro- 



°° ' nidia at the left. (.Atlur 



several -celled mass of tissue I'ringsheim,) 



15s. 



Portion ol thallus 

 of C o 1 e o c h ,t:- t e 

 sciitata, shn\\in'.j 

 four antheridia 

 formed from one 

 thallus cell ; a sin- 

 gle spermatozoidat 

 the li.ght. (After 

 I'ringsheim.) 



Ijefiire the zoospores are firmed, while in ledogonium only four 

 zoospores are formed direitlv from the egg. 



326. Asextial reproduction, li 



cells "III tlio plant may lorni /,<>'r^*^u 



vc|nii(hicli(in any of the oreen 

 ■ ciiiilrnis 1,1 a coll ictind oft and 



