28 



Veit Brecher Wittrock. 



But, on the contrary, ramification of the terminal cells without the for- 

 mation of new cells is not at all uncommon. In this manner the helic- 

 oids before mentioned, so characteristic especially in P. Cleveana nob., 

 are generally formed. A terminal cell, sometimes belonging to the 

 principal filament, but more frequently to a branch, sends forth at or 

 near its top -two or more, slender, irregularly shaped, more or less 

 crooked processes. These are not separated from the mother cell by 

 transversal walls, but will also in future belong as branchlets to the cell 

 from which they have been sent forth. Simultaneously with this forma- 

 tion of processes or branchlets, the greatest part of the chlorophyllaceous 

 contents of the terminal cell passes from the lower part of the cell into 

 its upper part. In this cell, two parts may consequently be easily 

 distinguished, viz. a lower one of the common cylindrical shape and 

 containing but a small quantity of chlorophyll-coloured protoplasm, and 

 an upper one of a varying shape, but regularly ramified and containing 

 an abundant supply of chlorophyll-coloured protoplasm. This upper part 

 is the helicoid (pi. 5, fig. 4 — 7, 0, 11, 12 li). The helicoids are most 

 frequently, but not always, formed by the ramification of terminal cells. 

 Sometimes, though very seldom, they may be formed by the ramification 

 of inclosed cells (pi. 5, fig. 1 A); and sometimes they may be formed 

 without any ramification, only by a peculiar development of the upper 

 part of an unbranched terminal cell; thus, that the upper part of the 

 cell grows more tapering and also richer in chlorophyll (pi. 5, fig. 1 A/). 

 Compare as to the rest paragraph 1, page 10. 



Having now almost completed the account of the formation of 

 branches in the cauloid, it may seem fit to enumerate here in one place 

 the different kinds of cauloid cells which do not, as a rule, form any 

 branches. These are as follows: l:o the top cells, 2:o the spore cells, 

 3:o the subsporal cells and 4:o the cells belonging to that degree of 

 branches which is, in each species, the highest (compare on this para- 

 graph 1, pag. 6, 7). Regarding the top cells we have, however, seen 

 above (pag. 26), that they now and then have the power to develop 

 branches. The spore cells, on the contrary, are always devoid of this 

 power. 1 ). But this does not prevent your finding, in almost all the 



l ) After this was written I have, however, found in P. ocdogonia (Mont.) 

 nob. (of which I have obtained the material missing before through the kind mediation 

 of my friend, D:r J. Kostafinski), that even spores sometimes have the power of 

 forming branches; see pi. 6, fig. 6, and the specific description of P. oedogon/a 

 (Mont.) nob. 



