76 



FIRST GROUP. — THALLOPHYTES. 



cff a pro-embryo, which is formedof simple cellular filaments, and from its resemblance 

 to the protonema of a moss might be called by that name. This protenema, which 

 has sometimes been described as a distinct species of the genus Chantransia, produces 

 unicellular gonidia, — small ovoid cells formed on the apices of branches, while the 

 batrachospermum-plant itself, which springs as a lateral branch from the protonema 



and has from the first a different 

 structure, ramification &c., forms no 

 gonidia. A similar pro-embryo, but 

 without gonidia, occurs in the fresh- 

 water LemaTiea, a plant of somewhat 

 complex structure which grows on 

 stones in mountain-streams, while 

 Batrachospennum occurs in the stiller 

 waters of cold springs. 



The spermatia are roundish cells 

 with a thin cell-wall. In Batracho- 

 spermuni, according to Siiodot, they 

 have the power of putting out a short 

 tube in the direction of the tricho- 

 gyne, when they are lying in its im- 

 mediate proximity. Usually they 

 attach themselves, one or more to- 

 gether, directly to the trichogyne and 

 mingle their protoplasm with the pro- 

 toplasm of that organ. The sper- 

 mada-cells which are formed in the 

 tissue of the thallus are released by 

 the conversion of the outer layer of 

 the wall of the mother-cell into 

 mucilage. In Batrachospermum the 

 mother-cells of the spermatia are 

 formed singly on the extremity of 

 long, articulated branches ; in the 

 Ceramieae they are crowded together 

 in large numbers on a common axis 

 as the terminal cells of a system of 

 very short branches ; these groups 

 of mother-cells of spermatia are 

 called antheridia [better spermogottia]. In Nitophyllum they are crowded together 

 on portions of the surface of the thallus which is formed of a single layer of cells ; 

 in the Corallineae they are formed in cavities that are grown over by the surrounding 

 tissue. 



We must not attempt in this place even a brief description of the several 

 families of the Florideae, and indeed many of them have been as yet insufficiently 

 investigated ; only the most noteworthy phenomena in the formation of the procarp 

 and in the process of fertilisation can be noticed in the following paragraphs. 



Fig. 48. Ploca 



Portion of a specimen 

 tetraspores t. 



k-ith branches bearing 



