126 MOSSES AND FERNS chap. 



respect Aneiira, where the base of the archegonium is confluent 

 with the cells of the thallus, offers an interesting transition 

 between the other Hepaticae, where the base of the archegonium 

 is entirely free, and Anthoceros. 



The archegonium rudiment divides into two tiers as in the 

 other Liverworts, and the peripheral cells divide longitudinally, 

 and here too the neck shows the six vertical peripheral rows 

 although it is completely sunk. Later, the limits of the neck 

 become often hard to determine, although by later divisions the 

 central cell is surrounded by a pretty definite layer of cells. The 

 axial cell divides into two of nearly equal size, but the inner one 

 soon increases in breadth more than the upper one. The latter 

 divides again by a transverse wall into an outer cell correspond- 

 ing to the cover cell of the ordinary hepatic archegonium, the 

 other to the primary neck canal cell. The cells of this central 

 row soon become clearly different from the other through their 

 more granular contents. The lower cell grows much faster 

 than the others and divides into the &2^q^ cell and the ventral 

 canal cell. The cover cell divides by a vertical wall into two 

 nearly equal cells, and these usually, but not always, divide 

 again, so that four cells arranged cross-wise form the apex of the 

 archegonium. In A. fusiformis in nearly ripe archegonia I 

 have sometimes been able to see but two of these cover cells, 

 but ordinarily four are present. The neck canal cell divides 

 first into two, and these then divide again, so that four cells are 

 formed. This was the ordinary number in A. fusiformis. In 

 a nearly ripe archegonium of A. IcBvis five neck canal cells were 

 seen, but in no cases so many as Janczewski ^ describes for this 

 species, where he says as many as twelve may be present. 



If the earlier divisions in the archegonium of AntJwceros are 

 compared with those of the other Hepaticae, the most striking 

 difference noticed is the separation of the cover cell. In the 

 latter the first division of the axial cell separates the cover cell 

 from an inner one, and by the division of the latter the primary 

 neck canal cell is cut off from the central cell. In AntJioceros 

 the neck canal cell is cut off from the outer, and not from the 

 inner cell. 



As the archegonium approaches maturity the cover cells 

 become very much distended and project strongly above the 

 surrounding cells. In stained microtome sections their walls 



1 



Janczewski (2), p. 415. 



