2 3 o BIOLOGICAL PROBLEMS 



essential nature of the relation which exists between 

 a raw material and the manufactured product. Speak- 

 ing as a botanist, who is naturally more interested in 

 the former than in the latter, one has certainly been 

 prone to overlook the extraordinarily intimate relation 

 that exists between the nature of the raw material and 

 the details of the process to which it is submitted in 

 conversion to the final state. Manufacturing processes 

 usually consist of a series of very complicated opera- 

 tions which require high technical skill combined with 

 very special plant. When a raw material is changed, 

 the process of manufacture no longer runs smoothly, 

 but is seriously disturbed. This can be illustrated by 

 a homely example. 



Every pipe smoker knows the inconvenience caused 

 him when he has to substitute an unfamiliar brand of 

 tobacco for that to which he is accustomed. Pipe 

 smoking stands for a manufacturing process, the 

 details of which vary from one brand to another. 

 The weed has to be packed differently in the bowl 

 according to the way the tobacco is cut and pressed. 

 Then there is the lighting of the pipe. Fine-cut 

 tobaccos catch fire at once, but coarse-cut varieties 

 often demand the use of two or three matches to get 

 properly alight. Moreover, the draught varies with the 

 brand. With a fine-cut tobacco an occasional gentle 

 puff is all that is required to keep it alight, and the 

 mind can be concentrated on other things; the devotee 

 of the coarser cuts, however, is kept continuously at 

 work in maintaining the forced draught which such 

 tobaccos demand. The result of changing brands 

 is that the fine-cut man takes days or weeks to learn 

 the knack of keeping a coarse-cut tobacco alight, 

 whilst the coarse-cut man will consume a pipeful of 

 fine tobacco in a few moments and also burn his 

 tongue. 



