SEEDLING 



Germination. A considerable number of seeds were germinated 

 in the laboratory. Seeds gathered in October, at the end of the 

 flowering season, first began to germinate in December, and from 

 that time on seedlings appeared intermittently. It is evident, there- 

 fore, that the seed requires a short period of rest before the new 

 growth begins. 



Seedlings were grown either in mud from their native habitat, 

 or in clean-washed sand, the latter being preferable, on account 

 of the numerous algae, bacteria, &c. which soon develop in the 

 former. The salt water used was taken from New Haven Harbor. 



Irmisch (1858) noticed in the achene of Ruppia rostellata a small, 

 slightly swollen, elongated area which he claimed was the place of 

 exit for the cotyledon and root on germination. Such a spot occurs 

 also in Ruppia mariiima, but I have been unable to ascertain def- 

 initely if this is the region which is ruptured at germination. In 

 most cases a more or less triangular area of the hard, dark-brown 

 covering is pushed off and the cotyledon and adventitious root 

 make their appearance (PI. XV, fig. 120). In figure 121 the whole 

 pericarp has been purposely removed to show the enormous hypo- 

 cotyl. 



Figure 120 shows a seedling about three days old. Here the 

 three vegetative organs are disclosed : the first foliage leaf is devel- 

 oped from the cotyledon, which becomes green ; the stem is formed 

 by the elongation of the hypocotyl ; and the root grows rapidly 

 downward, becoming abundantly furnished with root-hairs. 



In the case of the root, it is interesting to note that it exhibits 

 a general tendency to first grow upwards for a short time, only 

 later turning downward. The proportional growth of roots and 

 leaves seems to vary considerably (PI. XV, figs. 120, 121). 



Formation of Rootstock. Text-figs. 32 and 33 are drawings — 

 natural size — of seedlings grown in the laboratory in washed sand 

 and harbor water. The seeds were collected in January, being 

 extracted from mud taken from the bottom of a ditch where Ruppia 

 maritima grows and fruits abundantly, many of the parent plants 

 being even at that time in a green, flourishing condition. On 

 being placed in a warm room, germination occurred in a few days. 



