$6 SCIENCE PROGRESS 



organisation are needed to supply it, especially as pure strains 

 are not so catholic in their tastes for different localities as are 

 impure varieties in which natural selection can act. Moreover, 

 the cotton trade is not yet organised with the solidarity needed 

 for co-operation of this kind between the spinner and the grower. 

 At the same time, it is not easy to see how any such mechanical 

 device could be constructed ; the removal of weak hairs would 

 be simple, and is indeed already done, but the removal of strong 

 hairs — except by a process of elimination which broke all 

 the rest — would seem to be impossible; the other points of 

 difference, in weight, volume, and thickness of the hair, while 

 relatively great, are so small in absolute measure that they seem 

 to be beyond the reach of commercial machinery. 



To the writer's mind, however, there seems to be no doubt 

 that the invention of such a machine, or of any other method 

 achieving the same result, would constitute a real advance in 

 the technique of spinning. This conviction is strengthened 

 by the accidental origin of the discovery, as the result of the 

 convergence of several independent lines of research, and the 

 purpose of the present article is to present the possibility for 

 the co-operation of other investigators. 



