Reconstruction of Elementary Botanical Teaching. 191 
within certain limits; even very small quantities maybe utilised by 
the organism and the amount of assimilation varies directly with 
the supply up to a point where this particular material begins to 
have a toxic effect on the organism. It is important, therefore, 
that the supply of this material should be kept below the toxic 
concentration, which is not very high. 
The supply of synthesising energy also acts as a limiting factor 
but within wider limits. It is, as a rule, present in very small 
quantity, and the amount of assimilation depends chiefly on this 
factor. Plants, books and lecture notes are usually present in 
normal quantity. Assimilation varies directly with the supply of 
synthesising energy up to a point where the intensity of the energy 
has a detrimental effect on the organism and tends to burn or 
shrivel it. This extreme is never reached under natural conditions 
and occurs only rarely in artificial conditions. 
As mentioned above the supply of lecture note material has a 
toxic effect at a comparatively low concentration, it is clear, there¬ 
fore, that the synthesising energy is something different in kind. 
It is supplied by the teacher, and it is or should be the aim of any 
rearrangement of conditions for the organism to increase the 
supply of this synthesising energy. We must have teachers who 
teach because they must tell someone of the many wonderful 
things they have seen and know, not because the syllabus of a 
given university contains certain items of fact or theory which 
must be assimilated in order that the organism may be passed as 
healthy, after a superficial test by a body of experimentalists who 
have not as a rule had time to study either the organism or its 
environment in sufficient detail. 
The importance of the supply of synthesising energy acting as 
a limiting factor cannot be taken too seriously in the present dis¬ 
cussion, since it is the factor for which the teacher is directly 
responsible. 
Considering the generation of the energy at its source, it is 
clear that the radiations will have an illuminating effect only when 
the enthusiasm of the teacher reaches a red heat, and that the 
effect will increase as the enthusiasm increases up to white heat. 
This fact is pointed out by one of your contributors (op. cit. p. 106), 
and the generation of synthesising energy by enthusiasm is proved 
by the case he mentions. 
The direction of the radiation is another important point; 
to be effective the radiation must impinge upon the organism. 
