Cylindrocapsacece 81 



chloroplast is single, parietal, and disposed as part of an equatorial 

 band. Wittrock described the presence of two granule-like bodies 

 of a nutritive character, which he termed "nuclei," situated one 

 towards each end of the cell and outside the chloroplast. I have 

 examined quantities of this plant and find those bodies commonly 

 absent. 



B. tatrana Wittr. (fig. 25 A E) which has cells 6 9 p, in diameter, occurs in 

 mountain lakes and bogs. It resembles certain stages of species of Tribonema 

 (Conferva), and forms hypnospores (cfr fig. 25 E), but is more rightly placed 

 in the Ulotrichacese on account of its parietal chloroplast. Sometimes the 

 filaments become distinctly mucous. 



Family 4. CYLINDROCAPSACE.E. 



This family includes only a few plants belonging to the genus 

 Cylindrocapsa Keinsch. The thallus is filamentous and un- 

 branched, and resembles very much that of certain of the Ulotri- 

 chacea3. The cells are disposed in a single series, each one being 

 surrounded by a lamellose, gelatinous cell-wall, and the entire 

 filament is enclosed in a thick lamellose sheath. The cells 

 resemble very much those of the genus Hormospora in their 

 disposition and they may divide in the same manner as those of 

 Radio/Hum ; they are often ovoid or subtriangular in shape and 

 disposed in pairs at intervals along the filament. Each cell 

 possesses a parietal chloroplast with a single pyrenoid, but it is 

 often difficult to observe the nature of this chromatophore. 



Asexual reproduction occurs by zoogonidia formed singly, or 

 in twos or fours, from any of the cells of the filament. Each 

 zoogonidium is rounded or oval in form, possesses two cilia, a red 

 pigment-spot and two contractile vacuoles. 



Sexual reproduction takes place by means of well differentiated 

 male and female gametes. The male organs or antheridia are the 

 result of the active division of certain vegetative cells, and are 

 disposed in one, two, or four longitudinal series within the lamel- 

 lose sheath. Two antherozoids are produced in each antheridial 

 cell, similar in form to the zoogonidia, brownish red in colour, and 

 with two short cilia. The oogonia are developed by an increase in 

 size of the ordinary vegetative cells, each oogonium being large, 

 ovoidal in shape, and with a thick lamellose wall. A single 

 oosphere is present in each oogonium, which opens by a lateral 

 w. A. 6 



