26 i 
Absorption of Salts by Plants. 
A modification of this method was also employed in which the 
root grew in bent tubes with different parts of the same root in 
different solutions, and the same conclusion was reached in these 
experiments also. 
Ca 
By determinations of the ^ ratio of seeds he shows that the 
relative quantity of calcium in the seedling is independent of its 
behaviour in a pure magnesium salt solution, thus affording a further 
piece of evidence in favour of the view that the value of calcium lies 
in its effect at the surface between the absorbing membrane and 
the external solution, and is not due to chemical action inside the 
cell. With the further conclusions of this worker we intend dealing 
in the last section of this paper. 
The work of Osterhout and Hansteen has been supplemented 
by McCool (20) so as to comprise an investigation of the mutual 
antagonism of a larger number of kations. He experimented upon 
Wheat and Canada Field Peas. Seeds were germinated between 
damp filter papers and the seedlings so obtained were transferred 
to the culture jars containing the solution. The jars were not very 
large to judge from the photographs of the cultures, and several 
seedlings grew in one culture jar. The cultures appear to have 
been done singly, not even in duplicate, and the results given 
appear to be based on such single cultures. The plants were 
allowed to grow for from 21 to 30 days, after which the length 
and the fresh weight of shoots and roots were taken. By this 
method McCool has shown antagonism between calcium and a 
large number of other kations: magnesium, potassium, sodium, 
ammonium, barium and strontium. Magnesium and potassium 
were also found to exert an antitoxic effect upon the very poisonous 
barium, while magnesium, potassium and sodium were each found 
capable of reducing the toxicity of strontium. Mutual antagonism 
was also recorded between sodium and both potassium and 
ammonium. 
A few quantitative relations are also recorded, but it is obvious 
that the observations are spread over too wide a field to enable 
many exact quantitative measurements to be made. As the writer 
himself says, much remains to be done in this direction. 
In a further series of experiments the same worker has investi¬ 
gated the antitoxic action of various kations in regard to manganese. 
He finds the poisonous effect of manganese is counteracted by 
calcium, potassium, sodium and magnesium ions. 
