178 NEMATOPHYCEjE. 



FAMILY VI. ULOTRIOHE^3. 



Algae growing either in fresh water (Ulothrix), or marine or 

 sub-marine (Hormisrict) t or terrestrial (Hormidium, Schizo- 

 gonium), either of a bright green or yellowish green colour. 

 Threads very shortly articulate, simple, very rarely dividing into 

 single branches, free, now and then laterally connate in bands 

 (Schizogonium}. 



Primitive cells always many times longer than their diameter, 

 after repeated division equal, or shorter (rarely a little longer), 

 all fertile. Cell-membrane either thin (Ulothrix, Hormidium) 

 or thick, sometimes very thick, and distinctly lamellose (Hor- 

 miscia). Cell-contents at first effused, parietal, including a 

 starch granule, after simple or repeated division transmuted 

 into gonidia. 



Gonidia of two kinds, Macrogonidia sphaerical, ovoid, or 

 ovate-oblong, rounded at one pole, and acute at the other, fur- 

 nished with 2 or 4 vibratile cilia, often germinating in the 

 mother-cell without sexual fertilization. Microgonidia much 

 smaller, of similar form, furnished with two cilia at one ex- 

 tremity. Both kinds of zoogonidia produced within the cells of 

 the threads, emitted either by a poriforin opening in the mother- 

 cell, or by the splitting or breaking up of the mother-cell. 



For detailed information on this family consult Braun's " Rejuvenes- 

 cence" (Ray Society), pp. 148, 161, 184, 208, 223 ; Dr. A. Dodel, " die 

 Kraushaar-Alge," Ulothrix zonata, in Pringsheim's " Jahrbucher," t. x. ; 

 Cienkowsky " Zur Morphologie der Ulotricheen " (1876) ; Thuret, in 

 " Ann. des Sciences Naturelles," xiv. (1850), p. 222 ; and Dr. Braxton 

 Hicks, in " Quarterly Journal of Microscopical Science," 1861, p. 157. 



GENUS 66. HORXKZSCZA. Ares. (1866.) 



Articulate thread fixed by the basal cell, which is attenuated 

 downwards ; simple, or now and then emitting branchlets. 

 Cells abbreviated, enclosed by a thick cell-membrane, which is 

 often manifestly lamellose. Cell-contents green, parietal, 

 including an amylaceous granule. 



Propagation by rnacrogonidia and microgonidia. Eabh. 

 Alg. Eur. in. 361. 



