268 Ti-ansactions of the 



III.— On Bog Mosses. By E. Braithwaite, M.D., F.L.S. 



(Read before the Royal Microscopical Society, Nov. 1, 1871.) 

 Part II. 



Bepobe commencing the descriptive portion of our subject, it may 

 be well to enter a little more into detail with respect to the his- 

 tology of the interesting plants constituting the Sphagnaceae. The 

 pubhshed materials of which I have availed myseK in the study, 

 are the following, and to Prof. Lindberg, of Helsuigfors, I am 

 also deeply indebted for beautiful specimens of some of the rarer 

 species. 



1. Dozy — Bijdrage tot de Anatomie en Phytographie der 

 Sphagna. 1854. 



2. Schimper — Entwickelungs-geschichte der Torfmoose. 1858. 



3. Lindberg — Torfmossornas byggnad udbredning och syste- 

 matiska uppstallning. 1862. 



4. Kussow — Beitrage zur Kenntniss der Torfmoose. 1865. 

 The roots, which form only on the young plants, are chiefly of 



use in fixing them to floating objects, for as soon as branches shoot 

 forth, a part of these forming each fascicle drop perpendicularly 

 downward, and becoming appressed to the stem, are from their 

 hygroscopic quality far more effective than true roots, in trans- 

 mitting fluid to the other parts of the plants ; while the dense masses 

 formed by the aggregation of stems equally supersede the use of 

 roots as fixing organs. As the stem increases in size, the simple 

 flageller branches arise laterally from the uppermost leaves, and are 

 crowded together into a head or capitulum, which supplies fascicles 

 of branches to the stem below, by elongation of the internodes, 

 and keeps up its stock of young branches by constant renewals from 

 the growing point at the apex. The dichotomous ramification of a 

 Sphagnum depends on the annual production of an innovation, 

 which is a perfect repetition of the stem of the previous year, and 

 derives its origin from one of the lateral branches of the capitulum, 

 which rises upward and becomes elongated into a main axis. 



The number of branches in a fascicle seems tolerably constant in 

 each species, a part of these we may call the divergent branches, 

 which proceed at a right angle from the stem, then bend about the 

 middle and arch gracefully downward ; the rest we will term the 

 pendent branches, and these are longer, more attenuated, and fall 

 down from their point of origin in the fascicle, and he close to the 

 stem. A part of the divergent branches become condensed and 

 club-shaped to form the catkins of male flowers, and a few others 

 become fruit branches. 



The leaves of Bog mosses vary considerably on different parts 

 of the plant : the stem leaves are distant from each other, and usually 



