ANTHOCEROTALES 269 
later, in the well-known way, into elaters and spore-mother-cells, showing 
thus a partial sterilisation (Fig. 131 a). Subsequently the intercalary 
activity begins in the middle zone, and it adds by basipetal increments 
respectively to the columella, the archesporial layer, and the capsular wall. 
Such intercalary development may be held to have been of secondary 
origin from the region corresponding to the seta of other forms, and the 
Fic. 131. 
Notothylas Breutelit. A, longitudinal section of the basal region of an almost mature 
capsule, showing a short sterile columella derived from the endothecium. X130. B,a 
similar section, but without sterile columella. In the upper part the wall of the capsule 
can be distinguished from the sporogenous tissue, the cells of which are differentiated into 
spore-mother-cells (shaded), and elaters. Traced downwards, the central portion of the 
sporogenous tissue is continuous with the endothecium, while the peripheral portion comes 
from a layer of cells which have a common origin with the wall. X170. C, transverse 
section of a sporogonium like B, at the base of the fertile region ; the uniform sporogenous 
tissue (shaded) can be seen to be composed of four central groups of cells (endothecium) 
and a surrounding layer derived from the amphithecium. xX170. D, £, F,G, H, succes- 
sive transverse sections of a sporogonium, in which one of the four rows of cells of the 
endothecium is forming a sterile columella, left clear in G and 7. The origin of the 
amphithecial archesporium can be followed. X10. (After Lang.) 
primary condition of the sporogonium will thus be a more satisfactory 
basis for comparison with other Liverworts than its mature state. 
It might be difficult, in the absence of intermediate forms, to bring 
this peculiar sporogonium of Axthoceros into relation at all with those of 
other Liverworts. But within the Anthocerotales there is the genus 
NVotothylas, which bears sporogonia of small size, and of limited inter- 
calary growth, whereas in the other genera the large sporogonia appear 
