GERMINATION OF HIPPURIS VULGARIS. 445 
When the ripe fruit falls from the parent plant it floats on the water for a 
short time, and allows a certain measure of water-dispersal. Bird-dispersal 
also occurs, as in the cases here described, but whether either method is more 
normal is uncertain. 
The large embryo in the seed is straight, and lies with its hypocotyl 
directly below and directed towards the stopper. The first step in germi- 
nation is the gradual pushing out of this stopper by the elongation of the 
hypocotyl. This action is a leverage rather than a direct push, and in most 
cases the stopper remains attached at one point of its cireumference to the 
endocarp. The hypocotyl now appears as a blunt white body protruding 
Lo 
Fia. 
A-E. Early stages in germination of Hippuris. 
P, Oo c 
from the foramen of the fruit. Within a day or two it undergoes a positively 
geotropie curvature so that the tip is directed vertically downwards. Soon 
after this a ridge appears just behind the tip, and rapidly develops into a 
collar bearing a ring of horizontally-spreading root-hairs. Such a ring of 
hairs arising from the collet is not uncommon, especially among aquatic 
plants. Warming (in Bot. Zeit. Jahr. xli. p. 202) gives a list of plants in 
which it occurs. At this stage the upper part of the hypocotyl becomes 
green. Beyond the hairs the tip of the hypocotyl becomes differentiated into 
a central core and an outer transparent sheath. This is the initiation of the 
radicle, which now quickly elongates and penetrates the mud. 
