I30 MOSSES AND FERNS chap. 



the purposes of haustoria. Leitgeb -^ states that the foot arises 

 only from the lowest of the primary tiers of cells, but in most 

 of my sections of the earlier stages the fact that the foot was 

 composed of two distinct layers of cells, corresponding in 

 position to the two lower tiers of cells in the embryo, was very 

 obvious (Fig. 60, E). 



The origin of the archesporium in Anthoceros was in 

 the main correctly shown by Leitgeb,^ but I find that the 

 extent of the archesporium is less than he represents. In 

 PL I. Figs. 3 and 10 of his monograph on the Anthoceroteae, 

 he figures the archesporium as extending completely to the 

 base of the columella. A large number of sections were 

 examined, and in no case was this found to be so. Instead, it 

 was only from the cells surrounding the upper half of the 

 columella that the archesporium was formed. Previous to the 

 differentiation of the archesporium the four primary cells of the 

 columella divide by a series of transverse walls until there are 

 about four cells in each row. Radial walls also form in the 

 outer cells so that their number also increases, and the young 

 capsule consists of the central columella composed of four rows 

 of cells and a single layer of cells outside. The archesporium 

 now arises by a series of periclinal walls in the peripheral cells of 

 the upper half only of the capsule, and is thus seen to arise from 

 the peripheral cells of the capsule, and not from the central ones. 

 Fig. 60, E shows a longitudinal section of the sporogonium at 

 this stage. Three parts may be distinguished — the foot, the 

 capsule, and an intermediate zone between. This latter is 

 important, as it is from this that the meristematic part of the 

 older sporogonium is formed. With the separation of the 

 archesporium the apical growth ceases, and the future growth 

 is intercalary. 



In the capsule cell, divisions proceed rapidly in all its parts. 

 The original four rows of cells forming the columella increase 

 to sixteen, which is the normal number in the fully-developed 

 sporogonium. The archesporium, by the formation of a second 

 series of periclinal walls, becomes two-layered, and the wall 

 outside the archesporium becomes about four cells thick, the 

 outermost layer forming a distinct and well-developed epidermis. 



The foot grows rapidly in size, but the divisions are 

 very irregular, and finally it forms a large bulbous ap- 



1 Leitgeb (7), vol. v. ^ Leitgeb, /. 



c. 



