DEVELOPMENT, %3 
is not particularly distressed at a wet growing season, but 
he looks forward with hope to a relatively dry, hot period 
for the corn to ripen. Of great practical importance also 
is it to note the different effects of manures as particularly 
observed at Rothamsted ; some, such as nitrogenous ma- 
- nures, stimulating growth more especially ; others, such 
as the alkalis and superphosphates, being more particu- 
larly favorable to the ripening of the seed or the consoli- 
dation of the straw by the formation of woody fibre. 
Growth is the same throughout all plants, but the 
mode of development is much more specialized. In its 
initial stages, the atom of protoplasm that is to be the 
future potato plant, is not appreciably different from 
that which is destined to grow into a wheat plant or into 
a fruit tree. While growth is common to all plants and 
uniform in character, development is special and different, 
less or more, in the case of each particular species or kind 
of plant. Outward conditions greatly influence the 
amount of growth, while they have relatively less influ- 
ence on the extent, still less on the direction of develop- 
ment in the individual plant. 
Inheritance.—A particular kind of' plant, therefore, 
may retain its characteristics year after year, century 
after century, age after age, if the conditions are not 
greatly altered, because the successor follows, in the 
course of its development, the same lines as its predeces- 
sor did. It is thus by hereditary transmission that the 
’ characters of plants are perpetuated. 
Variation—Selection.—But the course of development 
in the offspring is not always and in all cases the same as 
in the parents. On the contrary, there is a certain range 
of variation, by virtue of which a seedling plant does not 
exactly reproduce either of the parental forms ; indeed, 
as it is of mixed origin, it could not be expected to do so. 
4 
