APPENDIX 617 



P. 98. The writer has investigated the development of the sporo- 

 phyte in Pallavicinia, Podomitrium, Calycularia, and Treubia. (Camp- 

 bell (34, 37, 39, 40).) 



In Pallavicinia (Campbell and Williams (37) ) the young embryo 

 develops a very conspicuous haustorium, which is composed of several 

 cells instead of being unicellular as in Aneura, and in Podomitrium 

 (Campbell (39) ) and Treubia (Campbell (40) ) the haustorium forms 

 a large mass of cells below the foot. In none of these genera is the 

 separation of the sporogenous area so early differentiated as in 

 Aneura. 



There is a good deal of variation shown in the development of the 

 sporophyte in different species of Pallavicinia. Thus in P. Zollingeri, 

 which belongs to the section Mitteriia, the sporogenous area in the 

 young capsule is quite limited and forms a convex disc, which in 

 vertical section appears as an arc composed of narrow cells arranged 

 in vertical rows, the tissue below forming a sort of columella, which 

 later disappears with the increased growth of the sporogenous tissue. 



P. radiculosa and P. Levieri show a larger amount of sporogenous 

 tissue in the young sporophyte and the capsule becomes very much 

 elongated, especially in the former species. These species belong to 

 the section Eupallavicinia. P. Zollingeri has a shorter capsule, which 

 is more clearly separated from the seta than is the case in any species 

 of Eupallavicinia that were examined ; and there is a distinct some- 

 what bulbous foot developed, while in Eupallavicinia the foot is much 

 less developed. In both respects Mittenia comes nearer to the genus 



M'orkia. 



In all of the species of Pallavicinia the apical portion of the capsule 

 wall is thicker than the lateral walls, this being most marked in 

 Eupallavicinia, where the apex is pointed and forms a beak some six 

 or eight cells deep, while the lateral walls of the capsule are composed 

 of but three or four layers of cells. 



Podomitrium Malaccense (Campbell (39) ) much resembles Palla- 

 vicinia in the development of the- sporophyte, but there is a small 

 apical elaterophore like that of Aneura, and the foot is clearly marked 

 by a constriction as it is in M'orkia or Calycularia. (See Campbell 



(34).) 



P. 98. In many cases, e.g., Pallavicinia Levieri, the calyptra is 

 not wholly derived from the venter of the archegonium, but the 

 tissue below the archegonium is involved so that with its growth 

 the unfertilised archegonia are carried up to the summit of the 

 calyptra. 



