2 Splacknidiwn rugosuin. 



Laing,* in which the author gives a brief note of his observations on 

 Splachnidium rugosum. 



Specimens collected by Harvey at the Cape and Australia have been 

 re-examined by us, as also those collected by Dr. Lyall in New Zealand, 

 and quoted by Harvey. In addition to these, we have examined specimens 

 from Seal Island, l Challenger Expedition ;' from the Cape, collected by 

 Mr. Boodle ; excellent spirit specimens from the same region by Mr. 

 Scott Elliott ; and from New Zealand by Dr. Berggren, all of them in the 

 British Museum. 



The PLANT of Splachnidium rugosum consists of from five to six 

 branches or fronds, which spring from a small conical disc, the base of 

 which rests on the substratum to which the plant is attached. Each 

 branch has a well-marked main axis of cylindrical form, which gives off 

 at irregular intervals smaller branches, similar in form and structure. The 

 surface of the thallus is marked with numerous pits containing hairs in 

 their young state, and, at a later stage, reproductive organs. 



THE MINUTE STRUCTURE OF THE THALLUS. Transverse sections of 

 a branch taken at any point between the apex and the base, but exclusive 

 of the pits just mentioned, show on the whole a uniform structure. The 

 external wall consists of rows of closely placed cells, on the inner side of 

 which lie strands of hyphal filaments surrounding a mass of mucilaginous 

 substance, which entirely fills the central part of the branch (plate II., fig. i). 

 Five layers of cells may be distinguished, the outer layers being clearly 

 defined from those that lie more internally by the shape of their cells. For 

 the sake of clearness in description, we will venture to call the two outer 

 layers epidermal, and the inner ones cortical layers. The cells of the 

 epidermal layers are small and approximately cubical in shape. They are 

 filled with a dense granular olive-brown protoplasm ; on staining with 

 carmine or picric aniline blue, a nucleus is apparent. The cells of the 

 cortical layers, when first formed, are polygonal ; at a later stage they 

 become ovate by unequal growth. The cell contents are olive-green when 

 young, changing to brown when maturity is reached. 



The strands of filaments lie, some immediately below and in contact 

 with the innermost cortical layer, while the remainder, becoming more and 

 more separated from one another, lie in the periphery of the mucilage 

 with which the central part of the branch is filled ; they run in all direc- 

 tions, but take, on the whole, a longitudinal course from base to apex. 

 Each strand consists of one large central filament, surrounded by a varying 

 number of small ones. The former are made up of elongated thin-walled 



f Observations on the Fucoidece of Banks 's Peninsula (Trans, and Proceedings of the 

 New Zealand Institute, vol. xviii., 1885). 



