THE STORY OF ARTIFICIAL SILK 
are then twisted into threads and wound on 
big bobbins. The finest filaments are made 
by pulling the filament as it comes out. 
They can now be made as fine as the fila- 
ments of the silkworm. 
Before cotton fibres can be used, they 
must be cleansed from oil, fat, wax and 
colouring matter. They must be boiled, 
bleached, dried and teased out. The yarn 
made from wood alone is a pale cream, 
while the yarn made from cotton is a bluish- 
white. The cotton yarn is 25 per cent. 
stronger than the wood pulp yarn. 
Wood fibre, we have learned, is a very 
strongly made substance. The microscope 
shows that it is made of peculiarly elongated 
cells—spindle-shaped and pointed at the ends. 
This sort of cell gives greater strength and 
tenacity than the structures that have 
spherical cells. Also, it gives greater density. 
You could, for instance, pack cartridges 
together more tightly than bullets. 
_ Nature designed a specially shaped cell 
in the making of trees. We have only 
recently appreciated this fact. There seems 
to be no limit to the number of new uses 
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