COLEOCH^TE. 



Ill 



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

 eral years 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 growth from a single cell at the central point, and grew 

 at the margin in all directions. Sometimes they are quite irregu- 

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

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

 carefully there will be found 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 coleocheete (sheathed hair). 



258. Fruiting stage of coleoclisete. — It is possible at some 

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

 the margin of this green disk. These have developed from a 

 fertilized egg which remained attached to the plant, and prob- 

 ably by this time the parent plant has lost its color. 



259. Zoospore stage. — This mass of tissue does not develop 

 directly into the circular green disk, but each of the cells forms 

 a zoospore. Here then, as 

 in oedogonium, we have an- 

 other stage of the plant in- 

 terpolated between the fer- 

 tilized egg and that stage 

 of the plant which bears the 

 gametes. But in coleochsete 

 we have a distinct advance in 

 this stage upon what is pres- 

 ent in oedogonium, for in 

 coleochaste the 

 egg develops 



several-celled mass of tissue Pringsheim.) 

 before the zoospores are formed, while in oedogonium only four 

 zoospores are formed directly from the egg. 



260. Asexual reproduction. — In asexual reproduction any of the green 

 cells on the plant may form zoogonida. The contents of a cell round off and 



Fig. 114. 

 Portion of thallus of Co- 

 leochsete scutata, showing 



fertilized ^™pty c^Us from which 



zoogonidia have escaped, 



first into a °?,^ fr°f ff * "" ; 7°|°- 



mdia at tlie left. (After 



Fig. 115. , 



Portion of thallus 

 of Coleochate 

 scutata, showing 

 four antheri'dia 

 formed from one 

 thallus cell ; a sin- 

 gle spennatozoidat 

 the right. (After 

 Pringsheim.) 



