580 The American Naturalist. [June, 
that a union among flowering plants is more significant than with the 
ferns and allied cryptogams. If this assumption seems reasonable, it 
is not unsafe to conclude that it is not easy to limit the time that the 
offspring of any union may exist. 
On the same basis it may be asserted that the wider the union the 
more vigorous the progeny, and the more certain it will be to succeed. 
This statement rests on a broad basis of fact. Darwin’s work on 
‘‘ Cross and Self Fertilization in the Vegetable Kingdom ” is a cor- 
toboration of the Statement, that ‘‘ Nature abhors continual close 
fertilization.” If the rule be reasonable among weed plants, it will 
appear even more so among domestic vegetation, in so far as wideness 
of fertilization is concerned. Nature has but comparatively few varie- 
ties. They may take the initial step, but be crowded out, the struggle 
being oftentimes too fierce. Among cultivated plants the conditions 
are very different. The plants are removed from the intense action of 
the law which determines the ‘survival of the fittest.” The weeds are 
the best fitted to survive, but the hoe befriends the weaker and better 
(for man) species. Cultivated plants, therefore, lead a life of compar- 
ative peace, and their energies are expended along the lines that 
the cultivator desires to follow. Variations appear, and are carefully 
watched and propagated, and in time a new sort is established. The 
conditions are vastly mare variable under which cultivated plants exist 
than those of their wild allies. This leads to a wide range of charac- 
teristics even in the same variety. Unions? therefore, are here more 
powerful, under the rule that wild is more potent than close fertilization. 
Each individual is the balance-sheet of a long series of forces, both of 
within and without. 
The two controlling laws of life, which for brevity’s sake may be 
stated as: Like produces like, and, like produces unlike, doubtless 
act everywhere. But the first prevails in the lower forms of plants 
while the second dominates over the higher. As an extreme instance 
note the human race with its millions of individuals, no two of which 
are unmistakably alike. Even here the greatest variations are in the 
more highly developed classes or nationalities, The type of gentleman 
is more variable than the type of the Hottentot. The dominant motive 
of the former is not so constant and all-absorbing as in the latter. 
The wild plant exerts all its powers to keep even with its rivals. The 
cultivated plant has thrown down its arms, and is active in building 
| To rear young through 

