On the Pithophorace^e. 



33 



pointing somewhat upwards, which is separated, when it has attained a 

 length which exceeds the diameter of the mother cell 2 — 5 times, from 

 its mother cell by a parting-wall placed at the base of the process, and 

 thus becomes an independent cell. This cell, the lowest one in each 

 branch, is consequently formed by cell-prolif ication. In most cases, 

 a longer or shorter series of cells is afterwards formed by this cell, 

 exactly in the same manner as the cells of the principal filament by the 

 first cauloid cell. In a couple of species, the system of ramification 

 does not gain any further development (in these, branches consequently 

 exist only of the l:st degree), but in the other, branches of the 2:d 

 degree are formed according to the same law as those of the l:st, and 

 in two even branches of the 3:rd degree exist. Most of the cells, the 

 top cells excepted, form branches (at least in the principal filament), 

 this being done acropetally, thus, that the formation of branches begins 

 in the lower and older cells, and proceeds to the upper and younger. In 

 the manner now indicated is formed an Ahja which is as to its cauloid 

 Cladopliora-Wke, i. e. consisting of ramified series of cells. Its rhi/oid 

 consists, as has been mentioned above, generally of only one cell, 

 growing in a direction opposite to that of the cauloid. This cell, which 

 is analogous with the root system in the higher plants (especially with 

 the tap-root of the Dicotyledonece) as to its morphological, but not its 

 physiological character, does consequently not serve as an attaching organ of 

 the thallus. The plant is most frequently not at all attached, and when it 

 is (as happens now and then), it is with the assistance of peculiar tendril- 

 like organs, developed from the cauloid and called, by me, he lie olds. When 

 the specimen has attained its full size, the formation of spores commences. 

 It is effected in the following manner. The upper part, 1 / 3 — 1 / s °f the mother 

 cell of the spore, is somewhat widened. The chlorophyll-coloured proto- 

 plasm in the lower, not widened part of the cell then passes, little by 

 little, into the upper and widened part, till it is quite filled with chloro- 

 phyll-coloured protoplasm. A transversal cell-wall is then little by little 

 (succedaneously) formed, just below the point where the widened part 

 of the cell commences. In this manner are formed one lower cell con- 

 taining but little protoplasm, almost devoid of chlorophyll, the so-called 

 subsporal cell, and one upper cell, rich in chlorophyll and reproductive, 

 the spore. Its shape is as a rule cask-like or cylindrically cask-like. *) 



') In some species of JPithophora the spores are rather often purely cylindrical. 

 The spores of this shape are formed in the same manner as the cask-like, only with 

 the diffe'rence that a widening of the upper part of the mother cell docs not take place. 

 Nova Acta Reg. Soc. Ups. Ser. III. 5 



