52 



Meeting held in the Municipal Buildings, June 9th, 1890, F. W. 

 Branson, F.I.C, F.C.S.,in the chair. 



' THE RED SEAWEEDS. 



HAROLD WAGER. 



The group of the red seaweeds, or Floridea, is one which is, in some 

 respects, sharply marked oil' from all other Algee, more especially as 

 regards the formation of the reproductive organs. It is possible, however, 

 to show that the red seaweeds are ultimately connected to the lower 

 unicellular foi-ms (of the Algce), and that they form the culminating 

 point of one of the lines of descent of their group. These plants have a 

 very varied and at the same time a somewhat simple structure. They 

 form branching filaments, tiat leaf-like expansions, which often exhibit a 

 simple venation, or branched in a very regular and symmetrical manner. 

 They have generally a delicate texture, and are divided up in such a 

 manner as to render them the most beautiful of the seaweeds. Most of 

 the Floridece contain a red colouring matter, but there are a few forms 

 which are of a green colour. In addition to the red, however, there is in 

 all the red seaweeds a green colouring matter, which can be extracted by 

 means of alcohol, and is evidently the same substance, or nearly so, as the 

 chlorophyll of the higher plants. The red pigment is insoluble in alcohol, 

 but can be extracted by water. The sexual methods of reproduction are 

 extremely interesting. They depend largely upon the mode of life of the 

 plant, and yet they exhibit an approach to what is obtained in the higher 

 flowering plants. The female organ consists of a central cell or group of 

 cells, surmounted by a long, or in some cases, a short hair-like structure, 

 known as the trichogyne. This structure may be compared to the pistil 

 of the higher plants. The male organs are borne in special cells of the 

 vegetative body, and consist of small rounded cells, which are, unlike the 

 same structure in the lower AlgcB, incapable of movement. These small 

 bodies may be compared to the pollen grains of the higher plants. They 

 are carried through the water by currents, and are brought into contact 

 with the trichogyne, to which they adhere firmly. The cell walls between 

 the two, fuses, and the contents of the male organ pass into the trichogyne, 

 and through the trichogyne to the cells below. These cells then develop 

 and "ive rise to spores, from which new plants eventually develop. In 

 some forms there is a suppression of the trichogyne in the majority of the 

 female organs, one or two only being developed, and these do the work for 

 the remainder. The female organ, to which a trichogyne is attached, 

 becomes fertilised, and then sends out tubes which pass through the 

 tissues to fertilise those which do not possess a trichogyne. In all cases 

 fertilisation results in the formation of a more or less complex fruit, in 

 which spores are formed, and from these new plants are developed. 



