242 REPORTS ON THE STATE OF SCIENCE.—1913. 
more or less reduced by means of anesthetics. We have not been 
sanguine enough to attempt to measure the vitality of a given set of 
plants by applying the test to its roots; we have not even ventured 
to attack preliminary questions, such as the comparative vitality of roots 
and stems or of their different parts. In spite of the fact that we are 
able to work under favourable conditions as regards apparatus and 
method, we are only too familiar with the difficulty of securing uni- 
formity of experimental conditions during the uninterrupted periods of 
time required for the systematic recording of a sufficient number of 
data. We have, therefore, refrained from embarking upon difficult 
problems such as that proposed to himself by Mr. Balls, although we 
are by no means convinced that it is incapable of solution after its 
necessary preliminaries have been mastered, and provided the observer 
can then devote to it the necessary time and attention. But as a 
practical proposition it certainly cannot be solved by sporadic or sum- 
mary experiments such as are sufficient to establish the validity of its 
principle. 
Hitherto our reports have been directed to the establishment of the 
method in principle, and in this respect we believe ourselves to have 
been successful; we have shown, e.g., that the voltage of blaze-currents 
and the vitality of seeds decline pari passu with their age. 
Our present report contains a detailed account of individual observa- 
tions carried out during the months of July and August to serve as an 
indication and sample of the procedure we think necessary to follow in 
working out the test as a practical method of measuring the vitality of 
seedlings. 
A repetition of the description of method, precautions, results, &c., 
is not possible now; we must refer for such description to previous 
publications, more especially to an article in the Journal of the Linnean 
Society, Vol. XXXVII., on the blaze-currents of vegetable tissues, 
and to my lectures on ‘ Signs of Life’ published by John Murray, 
1903. 
It is, however, necessary to say in preface to the following detailed 
protocols : 
1. That excitation by a single induction shock must be of given 
constant strength, not too weak when little or no response is obtained, 
nor too strong when after a large response the subsequent excitability is 
impaired. 
2. That it is convenient to have in circuit two galvanometers of 
different sensitiveness, so that small responses are read upon the more 
sensitive, large responses upon the less sensitive galvanometer. In the 
protocols G, is a less sensitive galvanometer of 5,000 ohms, G, is a 
more sensitive galvanometer of 70,000 ohms. 
3. The voltage of response and the resistance in circuit are to be 
calculated from the deflections through the plant and through a megohm 
of a known fraction (one-hundredth) of a volt. 
