240 



RHODOPHYCEAE 



obtained which can be used in the curing of leather and the 

 manufacture of size, and also for puddings and medicinal purposes. 



*GiGARTiNACEAE : Phyllophora {phyllo, leaf; phora, bear). Figs. 

 160, 161. 

 The stipitate fronds expand upwards into a rigid or membranous 

 flat lamina which is either simple or divided, whilst proHferations 

 may also arise from the margin or basal disks. Morphologically the 

 thallus is composed of oblong polygonal cells in the centre bounded 

 on the outside by cortical layers of minute, vertically seriate 

 assimilatory cells. In some species secondary tissue has been 

 observed near the axils of branches or at the base of the frond. The 





Fig. 160. Phyllophora Brodiaei. A, plant ( x ^). B, carpogonial branch ( x 250). 

 C, transverse section of antheridial thallus ( x 450). D, nemathecia with tetraspores 

 (x 125). (A, original; B-D, after Kylin.) 



plants are dioecious and the sex organs are borne in cavities m 

 small fertile leaflets that are attached to the main thallus, the carpo- 

 gonial leaflets, which are sessile or shortly stalked, arising laterally 

 from the stipitate part of the main blade. In P. memhranifolia the 

 carpogonial branch is three-celled and after fertilization gonimo- 

 blast filaments are formed which ramify in the tissues, finally 

 producing pedicellate or sessile cystocarps. In P. Brodiaei the 

 carpogonium fuses directly with the auxiliary cell and the carpo- 

 sporic generation is omitted. This method of reproduction must be 

 regarded as reduction from the ordinary process in so far as the usual 

 rhodophycean life cycle is concerned. The tetraspores are borne in 

 moniliform chains packed into wart-like excrescences or nemathecia 

 which are borne on the female sexual plant. In P. Brodiaei the 

 absence of carpospores led earlier investigators to regard the 



