04 SEAWEEDS 



a likeness to the tetraspores of the same group. 

 Many authors, in fact, describe unhesitatingly both 

 these bodies by the terms appropriate to Floridece. 

 The contention rests on no more than this slender 

 support and the suggestive influence of the employ- 

 ment of such terms as tetraspores, &c., for the Dictyo- 

 tacece. The absence of any observation of fertilisation 

 leaves the field open for such speculation. On the 

 other hand, no trichogyne has been observed, and 

 the presumptive female reproductive organs sug- 

 gest degeneration from Phceophycece very much 

 more than affinity with Floridece. The antheridia, 

 apart from the motionless character of the anthe- 

 rozoids, correspond better with similar bodies 

 among the Phceophycece, and the envelope en- 

 closing the sorus in Dictyota, while morphologically 

 not directly comparable with a conceptacle, yet 

 resembles it as much as it does any corresponding 

 body in the Floridece. The fancied resemblance to 

 tetraspores attributed to the non-sexual spores is 

 based merely on their number, though this is incon- 

 stant (as it is, however, among the Floridece). But 

 the spores are extruded without a membrane and 

 their condition is, to say the least, just as consistent 

 with loss of cilia as with loss of membrane a purely 

 physiological condition scarcely admissible in such 

 an argument. The vegetative organs are over- 

 whelmingly in favour of their character as Phceophycece. 

 If we take the Cutleriacece, in which the mode of 

 thallus development is different, as has been de- 

 scribed, we see all three sorts of reproductive bodies 

 ciliated, while in Dictyotacece all three are motionless. 



