126 BOTANICAL GAZETTE [AUGUST 
Covillea are capable of growing in water, at least for a time, and carry- 
ing on normal absorption there. 
In order to observe the effects of too great and too small a supply 
of water on plants growing in soil, seeds were sown in two receptacles 
measuring 23°™ in depth, and were treated as nearly alike as possible 
except as to the amount of water given to them. Both stood where 
they received sunlight through a wire screen during the entire day. 
One lot received a very large amount of water, manifestly much more 
than they required, and the other lot was given very little, so little 
that at times they seemed in danger of drying up. At such times 
they were given a little more water, after which it was withheld again. — 
All the plants flourished, but in the course of a few weeks there 
was a marked difference between those that had received an exces- 
sive supply and the ones that had received a meager supply of water. 
April rath, eight weeks after the seeds were sown, the plants were 
carefully washed and examined. The seedlings of both lots pre- 
sented a fine, healthy appearance, and the roots of both had reached 
the bottom of the receptacle in which they were growing and had 
spread out upon it. They differed most conspicuously in the develop- 
ment of stems and leaves (fig. 3). Those that had received an 
excessive amount of water measured approximately 2°™ more in 
height than those to which a meager supply had been given, and the 
leaves were both larger and more numerous, numbering from 6 to 10° 
in representative specimens of the former as against 4 to 8 in the 
latter; while the largest leaflets in the two lots measured respectively 
1.4 and 0.8°™ in length. Neither lot showed as strong a development 
of the root system as plants grown under the same conditions to which 
an abundant, but not maximum, supply of water had been given. 
Microscopic examination showed that while both lots were charac 
terized by abundance of root-hairs, these were most numerous and 
better developed on the roots that had received little water. 
It will be instructive to compare with this the record of two other 
lots of seedlings that had been under observation for a period of seve? 
weeks, during which one lot had been given an oversupply of water 
while the other received very little. On March 31st, when they were 
taken up and washed free from the soil in which they had grown, 
it was found that the plants to which little water had been given had 
