18 
than it is in the most of the cortex—about 0.3 normal. In the roots of most 
plants there is a slight but not appreciably interrupted increase in the turgor, 
from the epidermis inward; but this increase is no necessary condition for the 
ready movement of water, and in the Cocos we find in practice the lower turgor 
to be internal. : 
In the youngest cells of the embryonal tissue which can be plasmolysed the 
limit is 0.5 normal. In the cap the turgor is for the most part 0.25 normal; 
and in outside cells, as long as they are alive, it is no less. All these deter- 
minations were made on roots which were apparently healthy and active. 
In all my experiments on absorption by the roots homeopathic vials 
were used, of such a size that when filled to the proper point with water 
the weight was 40-45 grams. In the cork of each was cut a hole fitting 
the individual root to be used. The latter was freed from the ground, 
with the least possible damage, to such an extent as to permit the neces- 
sary downward inclination of the tip. It was then washed, and all loose 
remains of the cap were carefully removed from the part which was to be 
within the bottle. To insure the absence of any open wounds the whole 
exposed part of the root, except that which was to be within the bottle, 
was smeared with vaseline. Water enough was used to immerse more 
than the absorbing region of the root, and the bottom of the bottle was 
kept low enough to prevent the water from touching the cork. The root, 
with its bottle, was laid in half of a split joint of bamboo, to which the 
appropriate slope was given, and the other half of the joint closed over it, 
thus insuring cleanliness. The hole in the ground was covered with abaca 
leaves to prevent. unnatural warmth. All roots were left in this condi- 
tion for one or more days before determinations of weight began. 
After this time, when any initial disturbance in the rate of absorption 
was assumed to have passed, the hole and bamboo were opened, the bottle 
carefully removed, the root being touched by the bottle once to remove 
any free drops, and then a weighed bottle of water was substituted, the 
cork always remaining with the root. When all necessary care was 
taken to prevent wetting the cork, neither bottle needed to be open for 
more than five seconds, and the exposure of the root was even for a 
shorter time. The chief error in this method of experimentation is 
probably to be found in the variable amount of water adhering to the 
root, but experience shows that the results are reliable to a limit of 
1 centigram. 
The chief facts I endeavored to ascertain with regard to the absorption 
by the roots were the rate at which it normally takes place and the regular 
diurnal variation, if any, which may be found in this rate. I have also 
made some experiments on the absorption of solutions of potassium 
nitrate. 
With regard to the usual rate of absorption, as has been seen to obtain 
for the growth, the first preliminary series of experiments demonstrated 
that roots which to the eye appeared to be similar behaved very differently. 
Nor was there correlation between vigorous growth and rapid absorption. 
