FLOR1DE& 203 



with the carpogones, and convey to them the fertilising principle from 

 the trichophore. The result is that each carpogone develops into a 

 cystocarp containing carpospores. A single fertilising-tube may in this 

 way impregnate a number of carpogones. 



Schmitz describes the process of secondary impregnation in the more 

 highly developed Florideae as consisting in the fertile cells (carpogones) 

 entering into communication, through orifices in their cell-walls, with 

 certain special sterile cells rich in protoplasm, the auxiliary cells, to 

 which the fertilising material is brought from the trichophore by the 

 ooblastema-filaments. The details of this conjugation between the 

 auxiliary cells and the carpogones are subject to great variation in 

 different genera. In some cases the protoplasmic contents of the two 

 cells coalesce completely, while in others their nuclei still remain distinct 

 after conjugation. The carposperm, or cell resulting from this conjuga- 

 tion, then grows rapidly, and peripheral cells divide off from it, leaving 

 a large central cell which alone remains sterile, all the peripheral cells 

 developing into carpospores. In the Corallinaceae the ooblastema-fila- 

 ment enters into conjugation successively with several neighbouring 

 auxiliary cells. In a larger number of genera the process is as follows : 

 A short branch of the carpogone, usually consisting of three or four cells, 

 becomes attached laterally to a branch of the thallus, and curves in such 

 a way that the carpogone-cell is closely applied to the nearest auxiliary 

 cell, or reaches it by means of a short protuberance from one or both 

 of the conjugating cells. The entire oosphere, or at all events its nucleus, 

 then passes over into the auxiliary cell. In the Gigartinacese the auxiliary 

 cell itself becomes the central cell of the cystocarp. 



LITERATURE. 



Nageli u. Cramer Pflanzenphysiol. Untersuch., 1855, 1857. 



Pringsheim Monber. Bed. Akad. Wiss., 1855, p. 133 (Quart. Journ. Microsc. Sc. , 



1856, p. 124). 

 Rosanoff (Rhodospermin) Mem. Soc. Sc. Nat. Cherbourg, 1856; Ann. Sc. Nat., 



iv., 1865, p. 320 ; and Compt. Rend., Ixii., 1866, p. 831. 

 Van Tieghem Compt. Rend., Ixi., 1865, p. 804. 

 Solms-Laubach Bot. Zeit., 1867, p. 161. 

 Askenasy (Rhodospermin) Ibid. , p. 233. 

 Sorby (Rhodospermin) Journ. Microsc. Soc., 1871, p. 124. 

 Klein Flora, 1871, p. 161 ; and 1880, p. 65. 



Agardh Epicrisis Syst. Florid., 1876; and Florid. Morpho]. (with atlas), 1879. 

 Bornet and Thuret Notes Algologiques, fasc. i. and ii., 1876, 1880; and Etudes 



Phycol., 1878. 



Falkenberg Nachricht. Gesell. Wiss. Gottingen, 1879 and 1880. 

 Ambronn Bot. Zeit., 1880, p. 61 ; and Sitzber. Bot. Verein Brandenburg, 1880, 



p. 74. 



