146 BRAUN, ON UNICELLULAR ALG.E. 



*** Formed by the union of the contents of two conjugated cells : 

 Diatomaeeee ; 



■**** Produced within special organs: "gemmidia" in " cystocarps," 

 as in the Floridice (/). 



b. Gonidia motile by means of vibratile cilia, otherwise differing but little 



from the common shape of cells (oblong and rounded), Zoogonidia 

 (vulgo '' zoospores ") : 



a. Germinating (without fecundation), producing normal individuals : 



* Solitary : macrogonidia of Vaucheria, (Edogonium, Bulbochcetes, 



Cutleria ; gonidia of Coleochates, Chcetojihora, &c. ; 



** Numerous, arising from successive generations in the same cell 

 (telogonidia) : Characium, Ulothrix ; macrogonidia and (?) mi- 

 crogonidia of Ulva ; 



*** Arising in the same cell, in a group by the simultaneous division 

 of the cytoplasm (protoplasm) : Codium, Codiolum, Bryopsis, 

 llydrocytium, Chefloiiiorpha, Cladophora, Laminaria ; macrogo- 

 nidia of Hydrodictyon. 



(3. Germinating, but producing only depauperate individuals, which 

 soon perish (pauperculse) : microgonidia of (Edogonium, Bulbo- 

 chafes ; 



y. Sterile, neither germinating nor fecundating : microgonidia of Hy- 

 drodictyon, Pediastrtim, Stcphanosphcera, Chlamidococcus, Cutleria ; 



0. Fecundating (sjjermatoyonidia) :* 



* Produced in numbers in the same cell : Fucoidea ; 

 ** One in each cell : Floridea.'\ 



c. Gonidia motile by means of cilia, further removed from the nature of 



cells, filiform and twisted in spiral forms (spermatozoidia) : 



One formed in each cell : Characece, Muscoideee, Filices, Equise- 

 tacece, Lycopodiacece, Rhizocarpece. 



* The spermatozoids, as they are termed, of the Fucoidea, although, 

 since the experiments of Thuret and Pringsheim, no doubt can be enter- 

 tained as to their function, are widely different, with respect to their form, 

 from the spermatozoids of the higher Cryptogams, and agree in all points 

 with the germinating gonidia of the Ectocarpea;, Myrionemete, Laminariete, 

 &c. Agardh (Spec. gen. et ord. Alg. I, p. 9) terms the Zoogonidia in 

 general and the spermatogouidia of the Fucoidece in particular " Sporidia," 

 speaking of them in the following words : "The sporidia of the Fucoidea 

 are without doubt analogous, on the one hand, witli the sporidia of the 

 Zoospermea", and on the other with the spermatozoa of the Miisci, Hepaticce, 

 and Characece. It is of little moment whether their functions be the same 

 or different. That the most various functions may be assigned to analogous 

 organs is shown by very numerous examples. The pollen and spores are 

 the same organs, but differing in function." 



f That the spermatogouidia of the Florideee move by means of cilia, has 

 been noticed in several genera by Dcrbes and Solier ('Mem. sur la Physio- 

 logic dcs Algacs '). 



