564 ON SEEDLINGS 



Angrsecum macnlatom, 1 Lindl. 



Seed spindle- shaped with a thin transparent testa loosely 

 enveloping the central pear-shaped homogeneous embryo. 



Germination. The embryo increases considerably in size and 

 ruptures the testa from above downwards, the debris remaining 

 attached at the lower end. At this stage two or three adventitious 

 buds appear on the upper surface of the germ-tubercle; their 

 position is very variable, and they are often all at a considerable 

 distance from what we should imagine to be the position of the 

 primary axis of the embryo ; they all seem of the same nature, no 

 one showing any peculiarity. 



A rudimentary vascular bundle runs from the bases of the rudi- 

 ments of the leaves of these buds down into the axis of the tubercle, 

 the lower part of which, however, consists of undifferentiated cellular 

 tissue. 



The seedling is nourished by tufts of hairs which arise at 

 numerous points of the surface of the rapidly growing top-shaped 

 embryo. There is no trace of a primary root. The germ-tubercle 

 has now completed its development, the future plant is produced 

 from the adventitious buds. One of these develops more or less 

 directly into the leaf- and flower-bearing axis, the others follow a 

 uniform course of development and produce a branching system of 

 tubers. 



The young leaves of the bud are alternate and distichous as in 

 the adult plant ; they are reduced to minute deciduous scales, but 

 their position can be readily ascertained by a linear scar marking 

 their place of attachment. In the case of those which produce a 

 secondary tubercle the bud increases considerably in bulk, the 

 dilated axis bears distichously arranged leaf-scales in the axils of 

 which appear buds which undergo a development similar to that of 

 the axis on which they arose, thus producing a ramifying tuberous 

 system. The other adventitious bud often develops for a time like 

 its fellows, but sometimes immediately produces a leafy stem. In 

 the former case this is developed in the axis of a leaf -scale of a 

 secondary tubercle ; in the latter the growing point of the adventitious 

 bud itself develops into the leafy stem. The first two leaves are 

 brownish membranous scales, the third and fourth are also scales 

 but green, the fifth has a well-developed lamina and shows the form 

 of a complete leaf. These primary leaves are all sheathing and at 

 first enclosed one within the other, but they open out and extend 

 with the growth of the axis which bears them. 



1 Prillieux et Riviere, Ann. Sci. Nat. ser. iv. torn. v. (1856), p. 119, pi. 5-7. 



