104 BOTANICAL GAZETTE [avawst 
as has been shown in figs. 25, 26, are formed entirely independ: 
ently of spindie fibers. How then are the walls formed? 
It is certain that the film of protoplasm indicated in jig. 2 
thickens and finally gives place toa straight wall, at first delicate 
( fig. 27) but gradually becoming firmer until its cellulose nature 
is unmistakable. 
The phenomenon is typical of one of the processes recently 
discussed by Strasburger (’98), in which a cell wall is formedin 
the interior of the protoplasm. It appears as if the film of proto 
plasm exhibits the activities present in the ‘ Hautschicht” when 
it lays down or increases the thickness of a cell wall in the mat- 
ner known as apposition, involving, at least in part, the change 
of its own substance into cellulose. ; 
With the separation of its contents the spore-mother-cell as 
a unit ceases to exist,and a new set of activities begins that maj 
very properly be reserved for discussion in another paper. Some — 
interesting events take place in the spore as it ripens, but technical 
difficulties interfere greatly with their elucidation. : 
The peculiar fact that the sporogonium of Anthoceros 
presents spore-mother-cells in all stages of development makes 
it possible to contrast the times occupied by the various changes 
One cannot establish the actual duration of any process, bit . 
within certain limits it is possible to determine the relative periods 
of each event. It must be assumed that the rate of gre 
the spore-mother-cell to the period of the first division of 
chloroplast. The division of the chloroplast occupies 6- 
The nucleus is in synapsis 12-20 units. For 30-50 units thee 
has two chloroplasts. It takes about 2 5 units after synapsis © 
Produce conditions favorable for mitosis, The first miter 
occupies 1-3 units, and the two daughter nuclei rest for : 
