286 Bower .—Some Normal and Abnormal 
from the sporophyte without the intervention of spores 
(apospory). 
Passing to the description of the antheridia, these are pro- 
duced for the most part on the protonema, either laterally 
(Fig. 45 B), or terminally (Fig. 45 A); usually they are 
lateral as in Tr. pyxidifernm, and are seated on a short pedicel. 
They have never been seen to produce mature spermatozoids 
in this species, and the central tissue appears in the large 
majority of cases to be atrophied ; one or more of the cells at 
the apex of the antheridium is usually brown and apparently 
disorganised. These facts diminish in some measure the 
interest which would attach to the study of their structure, as 
these antheridia evidently do not attain a full normal develop- 
ment. Seen from the outside, the cells composing the wall of 
the antheridium are usually irregularly disposed, and form as 
elsewhere one layer surrounding the central mass ; the cell- 
walls often run obliquely (Fig. 45 A, B, Fig. 46), while at or 
near to the apex is often to be seen a cell which appears like 
a biconvex apical cell (x Fig. 46) 1 . The idea that this actually 
does represent an apical cell from which successive segments 
have been cut off is supported by observations of antheridia 
in course of development (Figs. 47 , 48, 49) ; but it is difficult 
to harmonise such arrangements as those here shown in the 
young state with the more mature structure sometimes seen in 
optical section in this plant (Fig. 50). It would be possible, 
combining these observations with Cramer’s, to draw a com- 
parison between these antheridia and those of the Mosses in 
respect of the arrangement of cells in the young antheridium ; 
but, on the other hand, it must be remembered that the 
antheridia in this species do not come to normal maturity ; that 
observations in Tr. pyxidifei'um , in which the antheridia are 
normally matured, do not entirely accord with those on 
Tr. alatum ; and that the order of the succession of septa does 
not appear to be constant in this species. On these grounds 
it cannot be held that these observations on the order of 
Compare Cramer, 1 . c. p. 8, Taf. i. Fig. 9 an. 
