62 Report of the Bryological Section. [Sess. 
different stages in the life-history of a moss, illustrating the 
same by means of lantern slides and diagrams of preparations 
which the members had made. 
Taking the spore as the beginning of each independent 
plant, it is found to consist of protoplasm, containing numer- 
ous chloroplasts, with two distinct coverings; the inner cover 
is thin, and is known as the endospore; the outer is tough 
and of a brown colour, and is known as the exospore. When 
seen under a magnification of about 750 diameters, the exo- 
spore of Hypnum rutabulum appears to be covered with very 
fine dots. An essential to the growth of the spore is moisture, 
which is absorbed till the spore expands and ruptures the 
exospore. The protoplasm, surrounded by the endospore, 
begins to protrude and grows outward in the form of a fila- 
ment. Before growth has proceeded very far, however, cell 
walls are formed in the filament, dividing it into cells (fig. 1). 
We observe that cell formation takes place outside of the spore. 
This is true of all the mosses with the exception of one small 
group, where cell division takes place within the spore, and 
before it is ruptured. 
This filament, or protonema as we may now call it, marks 
the second stage of the plant life. It has unlimited power of 
elongation by apical growth, and is divided into cells by oblique 
transverse septa lying in different planes (fig. 2). These septa 
are formed only in the apical cell, as growth by cell division 
does not take place. These cells, however, have the power of 
putting out, just behind the anterior principal septum, little 
protuberances, which are separated by a cell wall from the 
principal filament (fig. 3). Another cell wall may be formed 
which divides the protuberance into two cells. One of these 
cells may grow into a filament penetrating into the soil and 
becoming a rhizoid. These always become brown by absorp- 
tion of mineral matter. The other cell may grow out into a 
secondary filament, lying on the surface of the ground. This 
becomes green owing to the formation of chlorophyll. 
It is generally from these secondary filaments that the 
young moss plant is developed. The cell that is destined to 
give rise to a new plant puts out, behind its anterior septum, 
a protuberance. This is formed into a cell by a cell wall. 
A change in development now appears. Instead of elongating, 
