98 
Improvement of the Plants of the Farm. 
a greater weight per acre, and has h)nger roots than the older 
sorts. The white Belgian carrot yields the largest crop of any 
field sort, but the quality falls short. A seedsman claims to 
have produced a carrot which answers well on shallow soils ; and 
another has a " splendid variety, long, even, bulky, and of 
excellent feeding qualities. When tender and not grown to its 
full size, it is as good as any garden variety." 
The root-crops, like others, must be adapted to soil and 
climate. 
The potato is essentially a constant subject for the plant- 
improver. Mr. Darwin shows, in 'Animals and Plants under 
Domestication,' that the tubers have been greatly enlarged and 
improved since the introduction of the plant. The potato- 
disease brought into constant operation the principle that in- 
creased vigour is imparted by the crossing of varieties. Hence 
the vast number of varieties in cultivation. Mr. Robert Fenn, 
of Sulhampstead, Reading, has spent forty-five years in breeding 
potatoes of excellent quality, and generally of the early kinds. 
Among the descriptions he has sent me, one relates to a " very 
desirable variety, which is off the ground sufficiently early to 
grow turnips afterwards, to be fed off by sheep, and then sown 
with wheat, or winter vetches, or other crops." There is 
another variety which, he says, would suit Ireland well, as it 
does its duty quickly, and would be, if the growers would 
" buckle to," out of the way of their autumn rains, and would 
escape the disease. In describing his method, j\Ir. Fenn says, 
" I spent ten years during my earlier experiments in trying to 
raise superior varieties by seed from promiscuous berries, and 
never met with the least success," Magnum Bonum, raised by 
Mr. James Clarke, of Christchurch, Hants, being the only example 
of a fine variety raised by sowing seed at random. All expe- 
rience shows that the principles of plant-improvement require 
careful study. Mr. Fenn had spent ten years previously in the 
vain endeavour to improve the types of varieties by careful 
selection of the best forms of tubers, and he now knows that 
selection has not yet produced any new or really improved form 
of potato. The ash-leafed kidney sometimes develops lumps, 
which give it an appearance widely different from that of the 
true stock, but the lumpy ash-leaf nevertheless reproduces the 
true type. Selection has given us many very valuable and 
entirely distinct new forms of mangolds, turnips, or carrots; 
but potatoes cannot be moved from their original shape by 
selection, so that new and improved sorts can only be had by 
cross-fertilisation. I believe the sole exception to this rule 
consists in a selected sport from the Rector of Woodstock. 
The following details by Mr. Fenn contain useful hints for 
