AND GERMINATION OF ALG^E. 129 



wards formed one or several large cells, which do not usually 

 include the whole contents of the sphacela. These cells are 

 the antheridia of the S])hacelaria, and their contents, at first 

 brown, gradually lose all colour and appear indistinctly orga- 

 nized, assuming the aspect of a fine-granular, mucoid sub- 

 stance, obscurely subdivided into separate, roundish, colourless 

 corpuscles, and closely resembling the contents of the anthc- 

 ridiiim of a Moss previous to its opening. 



Shortly after the antheridium has reached this stage of 

 development, its membrane is suddenly protruded on one side 

 into a long tubular prolongation, which breaks through the 

 wall of the sphacela (fig. 25) and opens at the point. At the 

 same time an active struggling and swarming movement in 

 the contents of the antheridium begins to take place under the 

 eye of the observer ; and it is seen that the indistinct organi- 

 zation presented in the contents of the unopened antheridium, 

 was due to the existence of closely-packed, minute, colourless 

 corpuscles, crowded into the narrow space. 



Most of these corpuscles quickly escape, and quite iso- 

 lated from each other, through the tubular process, moving 

 spontaneously and freely with great rapidity in all directions. 

 Those left in the antheridium now having more space, exhibit 

 a distinct locomotion, although less rapid than that of the 

 corpuscles which have made their exit. 



In the spermatozoids left within the antheridium, the author 

 has observed motion for more than an hour, whilst the escaped 

 spermatozoids cease to move after a lew minutes. 



The movement of the spermatozoids, though in some 

 degree like that of zoospores, appears to difTer in this respect, 

 that the motion of zoospores is more uniform and continuous, 

 and that of the spermatozoids interrupted and jumping. 



The spermatozoids of Sphacelaria appear like very minute, 

 clear cells without any dark or coloured nucleus, and so far 

 present the most striking resemblance to the antheridian-cells 

 of the FloridecB ; but, on the other hand, they are furnished 

 with two cilia, like the spermatozoids of the Fucacecp, like 

 which they move very actively. They appear, therefore, to 

 constitute an intermediate form between the spermatoztnds of 

 the Fucacece and those of the Floridece, though as regards the 

 development of the antheridia within a single cell, and the 

 mode in which the antheridium opens, they are manifestly 

 more nearly allied to the former. 



The author has little hesitation in assigning the female sex 

 to those plants which bear lateral sessile spores, but does not 

 seem to have confirmed tliis by direct observation. He re- 

 marks that it is very probable that Sphacelaria tribuluides also 



VOL. IV. K 



