269 
Growth of Roots and Shoots. 
seed for the experiment, as its moistened endosperm acts to 
a considerable extent as a water-reservoir for the seedling : 
but even in Zea Mays the seedlings grew much better when 
the soaked seeds were laid on damp plates of burnt clay. In 
this case, though the most strongly developed root hung 
freely down in the damp air, it was impossible to prevent 
the contact of the finer roots with the damp plate ; but since, 
in consequence of their positive geotropism, they nearly all 
had their apices pressing against the surface of the plate, the 
portions bearing the root-hairs were for the most part not in 
contact with the plate, but arched in the air. 
In the case of Vicia Faba , I found it advantageous to place 
each seedling with one cotyledon resting on some moist sand 
in a very small porcelain dish, so that the tap-root grew over 
the edge of the dish into the damp air, the sand being moistened 
every day or two by means of a pipette : the seedling was 
thus adequately supplied with water, although it was im- 
possible for the tap-root to absorb any in the liquid form. 
The details of the arrangement of the experiment were as 
follows : A number (a multiple of 3) of tubulated bell-jars of 
equal size were used : each bell-jar had a clear width of 
15-5 cm., and a clear height of 1 6 cm. to the tubulure, and 
it stood in a porcelain saucer 20*5 cm. in diameter containing 
enough water to cover the rim of the bell-jar. Inside each 
bell-jar was an inverted flower-pot, of about two-thirds the 
height of the bell-jar, and on this was placed either a glass 
dish or a circular porous earthenware plate, accordingly as 
a dry or a damp substratum was required. The inner sur- 
face of the bell-jar was sprinkled with drops of water. In 
order to provide a slight supply of air, the tubulure of the 
bell-jar was covered by an inverted glass beaker with a lip. 
The bell-jars were arranged in three series. In those of 
the first series were placed the normal seedlings, either 
altogether uninjured ( Zea Mays ) or with one cotyledon 
removed ( Vicia Faba ) : in both cases plumule and radicle 
were intact and could develop unhindered. In those of the 
second series were placed seedlings in which the plumule had 
