ULOT1UCHE.E. 179 



The filaments are sometimes cylindrical, sometimes tornlose like a 

 rosary, in consequence of the barrel-like inflation of the separate cells; 

 sometimes stretched out, sometimes frilled and interlacing each other, 

 with a relatively thicker stratified membrane. Vegetative or asexual re- 

 production is effected by macrozoospores, which originate 1-4 in a cell, 

 and after becoming covered with a transparent bladder make their exit 

 through an opening formed in the lateral wall of the mother-cell. The 

 macrozoospores are of a thick, short, pear-shape, furnished with four 

 cilia, a coloured spot, and a contractile vacuole. After a time they 

 come to rest, and fixing themselves by the mouth end, they lose their 

 cilia and envelope themselves in a membrane. The fixed end developes 

 into a root-like, colourless organ of attachment; the free end growing 

 into a club-shaped plantlet, through the cell, dividing into two by a cross 

 partition, and each of these again in two, and so further. Sexual repro- 

 duction arises through repeated bipartitiou in each cell, from 8-32 and 

 more, smaller microzoospores being produced. They have only two 

 cilia, and after a swarming for a time they conjugate laterally in pairs, 

 forming a zygospore, which attaches itself by the end corresponding to 

 the mouth of the microzoospore. It grows very slowly, and finally 

 breaks up by the simultaneous division of its plasma into 2-14 swarm- 

 spores, which constitute the beginning of a new sexual generation. If 

 any of the microzoospores remain behind in the mother cells, they are 

 able, without copulation, to germinate and grow into independent plants 

 which may be seen singly or in groups projecting from the mother- 

 cells. 



Hormiscia moniliformis. (Kutz.} Rabh. Alg. Eur. in., 361. 



Pale green, more or less crispate, often mixed with other 

 Alga? ; cells equal or a little shorter than their diameter ; cell- 

 membrane thick, colourless, somewhat lamellose, more or less 

 constricted at the septa. 



SIZE. Cells 011- < 014 mm. diam. 



Ulothrix moniliformis, Kutz. Tab. Phy. ii., t. 88. Kirch. Alg. 

 Schl. p. 76. 



In swamps, amongst Sphagnum, &c. 



Plate LXX. jig. 1. Portions of threads of Hormiscia moniliformis 

 X 400 diam. 



Hormiscia zonata. {Web. Sf M.) Aresch. Obs. p. 12. 



More or less bright green, mucous, two or three feet long, 

 often less, either floating or interwoven, sterile cells equal, or 

 half their diameter ; fructiferous cells usually a little longer 

 than broad ; cell-nienibrane thick, slightly constricted at the 

 septa. 



SIZE. Cells 012--04nim. ; macrozoospores -012--018 x '01 

 012 mm. ; microzoospores 'OOS-'Ol x '004--007 mm. 



Rabh. Alg. Eur. iii., 362. 



Ulothrix zonata, Kutz. Tab. Phy. ii., t. 90, f. 2. Kirch. Alg. 

 Schl. p. 76. Dodel in Prings. Jahrb. t. x., pi. i.-vm. 



Lyngbya zonata, Hass. Alg. 220, t. 59, f. 1-6. 



2 c 



