RAIN ON THE ROOT CROPS, 163 



the parent wild navcw whose pccuh'aritics ah'eady con- 

 tained them all potentially in the germ. To this day, 

 cither turnips or beets which 'break,' as we call it — that 

 is to say, which flower at the natural period — become 

 small and shrunken ; because the original store of food- 

 stuffs was laid by in the root for the flowering season ; 

 and when the blossoms come out the plant has practi- 

 cally reverted to its primitive condition. Similarly with 

 the cabbage : we have here adopted a closely related 

 variety — one can hardly call it a species, the two arc so 

 much alike — with smooth thickish foliage and a peren- 

 nial stock ; and while its flowers, roots, and seeds remain 

 unaltered, we have diverted its leaves into a solid head, 

 and produced from them the various cabbages and curly 

 kales of our gardeners. On the other hand, when we 

 choose to fix ourselves upon the blossoms alone, we can 

 make (or rather continuously select) a diseased form 

 with overfed abortive buds, which gives us from the self- 

 same stock our cauliflowers and broccoli. So one can 

 readily see why the rain which suits the narrow fibrous 

 rootlets of the charlock, and does not hurt even the 

 simple wild navcw, rots and destroys the big artificially 

 plimmed-out tap-root of our cultivated turnips. 



The other crucifers less closely related to the true 

 cabbages exemplify the same principle even more widely, 

 and cast much interesting side-light on the strong and 

 weak points of the analogy between man's conscious 

 selective action and the unconscious preference of nature 

 for the best adapted varieties. Scurvy-grass is a cru- 

 cifer somewhat more advanced in type than the cabbage- 

 worts, in that its flowers are white instead of yellow ; 

 and from one of its more distant south-eastern relatives 



M 2 



