134 NEMATOPHYCE.E. 



are the young spores, which undergo a marvellous variety of transforma- 

 tions. At first they are contiguous, but as they contract they become 

 free, though variable in shape, and with their chlorophyll distributed in 

 a thousand different ways. Finally they become spherical and almost 

 completely filled with chlorophyll interspersed with some starch granules, 

 and covered with a thin, smooth layer of plastic matter, but not with a 

 cellulose membrane. 



" Long before the foregoing process has taken place, the cell-wall 

 proper of the thread has undergone some peculiar chemical alterations, 

 all tending to its final dissolution to free the fully-developed spores. 

 Previous to this, however, little apertures are formed in it at certain 

 points, varying in diameter from one 500th to one 300th of a line. 



" All the cellules of the same filament do not undergo the modifica- 

 tions described. In a large number of them the phenomena are quite 

 different, the green rings, interspersed with colourless vacuoles, 

 gradually change to a reddish yellow, and the grains of starch dis- 

 appear. Soon the coloured matter thus formed becomes granular, and 

 is finally broken up into innumerable rod-like corpuscles." 



Thus the cycle is completed, and we need not pursue the abstract 

 further. Plate LII. will serve to illustrate the various changes. 



Sphaeroplea annulina. {Roth.) Ag. Syst. p. 76. 



Green, yellowish, brick-red, or scarlet, cells 8 to 10 or 20 

 times as long as broad, with 20 to 30 chlorophyllose rings in 

 each cell; spores at length densely seriate, rarely disposed 

 irregularly, at first green, afterwards olive-brown, and then 

 red. 



SIZE. Threads '036-'07 mm. cliam., oospore '018-'036 mm. 



Rabh. Alg. Eur. iii., p. 318. Rabh. Alg. ex. 309, 455, 147. 

 Cohn, in Acad. Borl. 1855, p. 335. Ann. des. Sci. Nat. 4 ser. 

 (1856) v., t. 12-13. Cienkowski, Bot. Zeit. (1855), p. 777. 

 Fresenius Bot. Zeit (1851), p. 241. Braun, Rejuvenescence 

 p. 164,271,281. 



Conferva annulina, Roth. Cat. iii., p. 7. 



In quarries, pits, or inundated fields. 



Cohii has remar-ked that whereas most confervoid Algse vegetate by 

 repeated subdivision of the terminal cell, being at some time or other 

 attached by the base, the present has both extremities alike, and 

 neither of them rooting, moreover the vegetation is carried on by 

 sub-division of the central cells, so that the terminal cells remain the 

 oldest. 



Plate Lll. fig. 1. Portion of filament of Sph&roplea annulina with 

 the green cytioplasm in rings X 400. Fig. 2, cells showing the forma- 

 tion of spermatozoids X 400 with escaped spermatozoids s below. Fig. 

 3, spores having acquired a globose form being fertilized by sperma- 

 tozoids. Fig. 5, spores in an earlier stage. Fig. 8, isolated spore with 

 spermatozoid attached. Fig. 6, mature spores, having acquired an 

 orange colour and stellate outline, the primary membrane is detached 

 X 400. Fig. 7, cells showing arrangement of mature spores X 300. 

 Fig. 4, resting spore in various stages ; a, mature ; b, divided into 2 ; c 

 and d, further subdivided. Fig. 9, zoogonidia X 400. Fig. 10, germina- 

 tion of zoogonidia X 400. All except Fig. 7 after Cohn. 



