1Q08] Observations ox Sekdling Plants 167 



the reserve food is assimilated (several Cruciferce). Very peculiar 

 is the structure of the cotyledon in several Monocotyledottes , 

 for instance the Graminecv, where a part of the cotyledon is 

 developed as a flat, shield-shaped origan, the so-called scutellum, 

 whose function it is to absorb the food-substances of the 

 endosperm ; a similar organ occurs, also, in Palms, Conwiclinacece, 

 Canna, etc., where it represents the apex of the cotyledon. 



It is, therefore, very natural that the cotyledons exhibit a 

 number of forms depending upon their function ; beside that 

 their varied position in the seed necessarily exercises some 

 influence upon the outline of their leaf-blades. However, the 

 cotyledons are not the only part of the seedling in which modifica- 

 tions as to structure and function may be observed; the primary 

 root and the hypocotyl exhibit, also, some certain types of 

 development, which are of no small interest. The root, for 

 instance, may develop as a nutritive or a storage-root; or it may 

 be the only organ by which the vegetative reproduction takes 

 place in the first season, as in Rhexia. Finally, the hypocotyl 

 may persist during the whole life of the plant or die off after the 

 first season ; it may persist as an ordinary stem, or develop as an 

 organ for storing nutritive matters. It is, also, important to 

 notice the position and vitality of the plumule ; most frequently 

 it gives rise to the main stem above ground, but not a few cases 

 are known, where it stays under ground during the first year, 

 developing into a rhizome; or, it lives only one season, after 

 which it becomes replaced V>y buds from the axils of the cotyledons. 

 In this way we must expect to find a rich illustration of biologic 

 plant-types by merely examining seedlings; and, if we follow 

 the successive development of these same seedlings, we are grad- 

 ually led into that inost interesting chapter of botany, which 

 teaches us about the morphology of the shoot with its innumerable 

 variations in respect to position anfl form of the vegetative and 

 floral organs. 



In the present paper I intend only to describe some types 

 of seedlings during the first year of their growth, and we might 

 begin with the M onocotyledones . 



Characteristic of the seedlings of this class of plants is the 

 presence of a single cotyledon, which may be epigeic or hypogeic, 

 and the short duration of the primary root . 



A very simple type is represented by Ai^ave (Fig. 1). We 

 notice in this that the primary root does not become arrested 

 in its development so early as in most of the other Monocotyle- 

 dones, but that it attains quite a considerable length; the 

 cotyledon is thread-like and forms a sharp knee for penetrating 

 the soil, while the apex remains enclosed in the seed until the 

 endosperm has become absorbed; after that the apex of the 



