ERRORS TO BE AVOIDED III 
quantitative work, and are therefore discussed here. 
The more apparent ones need not be mentioned, since 
they are sure to suggest themselves to any user of the 
method here presented. 
In the use of this quantitative method, as in most 
procedures involving numerous factors, a technique, 
which seems at the outset highly complicated, becomes 
with practice easy to carry out. Its inclusion as part 
of the experimental routine of the working physiologist 
is therefore justified. To facilitate such inclusion is 
the purpose of this manual. 
