b* SYDNEY n. VINES. 



that they are nearly right angles. The result of these divisions 

 is tliat the emhryo consists of four cells. Of these, according to 

 Hofmeister (fig. 6), in Pteris aquil'nia, the anterior inferior cell 

 is the one from which the first leaf (cotyledon) is developed, as 

 also the apical cell of the stem, the posterior inferior gives rise 

 to the root, and the two superior cells together form the foot. 

 He considers that in Aspidium fHx-mas the anterior inferior 

 cell gives rise, as in Pteris, to the first leaf and to the apical cell 

 of the stem, that the root is developed from the posterior 

 superior cell, the foot from the anterior superior cell, and that 

 the posterior inferior cell only grows to a slight extent, and 

 does not form " a detached portion of the germ-j)lant, but forms 

 the cortical portion between the back of the first frond and the 

 first root." 



Hofmeister's account above given of the development of the 

 embryo of Pteris presents the difficulty which has already been 

 met with in the consideration of Hanstein's account of the 

 development of the embryo of Marsilia, viz. the origin of a 

 portion of the foot from the anterior of the two cells into which 

 the oosphere primarily divides. The account given by him of 

 the development of the embryo of Aspidium is apparently in- 

 complete, and presents the same difficulty as the preceding. 

 Kny's recent investigations, to which allusion has already been 

 made, aflford some clue to a more correct interpretation of the 

 facts. Kny finds that the oosphere of Ceratopteris gives rise 

 by division to four cells, which lie in a plane parallel to that of 

 the prothallus, two of these cells being anterior and two 

 posterior. The two anterior cells produce the first frond, and 

 later, the apical cell of the stem. Prom one of the posterior 

 cells the root arises, from the other, the foot. 



Applying these results to the observations of Hofmeister, it 

 may probably be correctly stated that the two anterior cells of 

 the embryo of Pteris give rise to the first leaf and to the apical 

 cell of the stem, and tliat of the posterior cells, the sui)eri()r forms 

 the foot, the inferior the root. In the case of Aspidium it might 

 equally be said that the two anterior cells give rise to the first 

 leaf and to the apical cell of the stem, and that probably the foot 

 is here really formed by the posterior inferior segment, to which 

 Hofmeister assigned no special function, the root being derived 

 from the posterior superior segment. 



In the Pi(|uisetaceae the first division of the oosphere is in a 

 plane, which is somewhat inclined to the longitudinal axis of the 

 archegonium,^ and septa at right angles to the primary Wiill subdi- 

 vide the two cells. At this stage the embryo consists of four cells 

 arranged as the quadrants of a sphere. Prom the two lower the 

 1 Hofmeister, loc. cit,. p. 300. • 



