94 MOSSES AND FERNS CHAP. 



very short, and the archegonia, which are only produced in 

 small numbers (usually not more than six to eight), are close 

 together and surrounded by an irregular sort of envelope 

 formed by the more or less incurved and very much laciniated 

 margins of the branch. Secondary hair-like growths are also 

 formed, so that to the naked eye the archegonial receptacles 

 appear as densely fringed and flattened tufts upon the sides of 

 the larger branches. 



The archegonium of Fossombronia (Fig. 44) closely re- 

 sembles that of Sphcerocarpus, but it ordinarily has but five 

 peripheral rows of neck-cells, as in most of the Jungerman- 

 niales. Occasionally, however, there may be six rows, as in 

 Sphcurocarpus. 



Janczewski ( i ) followed very carefully the development of 

 the archegonium in Pellia epiphylla, which differs a good deal 

 from that of Aneura. The archegonia are formed in groups 

 just back of the apex, but he does not seem to have been able to 

 detect any relation between them and the segments of the 

 apical cell such as obtains in Aneura, but it seems probable that 

 such a relation does exist. After the archegonium mother 

 cell is cut off, it does not at once divide by vertical walls, but 

 there is first cut off a pedicel, after which the upper cell under- 

 goes the usual divisions. Of the three peripheral cells one is 

 much smaller and does not as a rule divide longitudinally, so 

 that the neck has normally but five rows of cells instead of six, 

 as in the Marchantiacese. Owing to the formation of the 

 pedicel, the archegonium is quite free at the base, and like that 

 of Aneura the wall of the venter is two-layered. The neck 

 becomes very long, and, according to Janczewski, the number 

 of neck canal cells may reach sixteen or even eighteen. 



The Sporophyte 



The earliest stages in the embryo are not perfectly known. 

 Kienitz-Gerloff (i) investigated Metzgeria furcata and Leit- 

 geb ((7), III) species of Aneura. In both of these the first 

 division in the embryo separates an upper cell, from which 

 capsule and seta develop, from a lower cell, which forms a 

 more or less conspicuous appendage at the base of the foot. 

 The earliest divisions in the upper part are not known, but it 

 soon becomes a cylindrical body consisting of several tiers of 



