RHODOPHYCE^, OR FLORIDA 247 



from the colour of the chromatophores, which is in 

 perfect agreement, but this is of purely physiological 

 significance. On the other hand intercalary divisions 

 occur in the cells of the thallus of Bangiacccc, and 

 though these occur also in Nitophyllum, Corallincce, 

 &c., the argument is not in favour of inclusion on 

 this ground. The pits between the thallus cells of 

 Ehodophycccc are also absent from Bangiacccc. Beyond 

 colour therefore there is little support to be gained 

 from the character of the thallus in favour of 

 inclusion. 



The Reproductive Organs. The cells that become 

 the female reproductive organs are indistinguishable 

 from the ordinary thallus cells. The process of special- 

 isation consists in a slight increase in size, but of no 

 particular alteration in shape, except the acquisition of 

 a very short lateral protuberance, called the homologue 

 of a trichogyne by those who favour the inclusion of 

 the order among the red seaweeds. The antheridia 

 produce motionless unciliated pollinoids. In Ery- 

 throtrichia one of the thallus cells produces a small 

 superficial cell, which is segmented off and becomes 

 the mother-cell of a pollinoid. There is here a certain 

 resemblance to the Rlwdophycecc, but in Bangia and 

 Porphyra the pollinoids are produced by the repeated 

 division (in all directions) of one of the thallus cells 

 which has gradually lost its colour. Numerous small 

 pollinoids are thus produced and set free by the dis- 

 solution of the membranes of the parent cells. The 

 pollinoid fertilises the female cell on attaching itself 

 to the short protuberance (trichogyne). An open 

 communication is effected, and the contents of the 



