42 ELEMENTARY BIOLOGY. [VI. 



small cortical cells. The nodes are the multicellular parti- 

 tions between these chambers. The branches are altogether 

 similar in structure to the main stem. The leaves are 

 also similar to the stem, so far as they consist of axial and 

 cortical cells, but they differ in the form and proportions 

 of these cells, as well as in the fact that the summit, 

 or free end, of the leaf is always a much-elongated pointed 

 cell. The branches spring from the re-entering angle between 

 the stem and the leaf, which is termed the axilla of the 

 leaf; and, in the same position, at the fruiting season of 

 the plant are found the reproductive organs. These are of 

 two kinds, the one large and oval, the sporangia or spore- 

 fruits, the other smaller and globular, the antheridia Both, 

 when ripe, have an orange-red colour, and are seated upon 

 a short stalk. 



If a growing plant be watched, it will be found that 

 it constantly increases in length in two ways. New nodes, 

 internodes, and whorls of appendages are constantly be- 

 coming obvious at the base of the terminal bud ; and these 

 appendages increase in size and become more and more 

 widely separated, until they are as large and as far apart 

 as in the oldest parts of the plant. The appendages at first 

 consist exclusively of leaves and root-filaments (rhizoids), 

 and it is only when these have attained their full size 

 that branches, spore-fruits and antheridia are developed in 

 their axillae. Sometimes rounded cellular masses appear in 

 the axillae of the leaves, and, becoming detached, grow into 

 new plants. These are comparable to the bulbs of higher 

 plants. 



If the innermost part of the terminal bud, which con- 

 stitutes the free end of the axis, or stem, be examined, 

 it will be found to be formed by a single nucleated cell, 

 separated by a transverse septum from another. Beneath 

 this last follows another cell, which has already undergone 



