ABSTRACT

Plants when first subjected to culture, even in their native country, cannot fail to be exposed to greatly changed conditions of life, more especially from growing in cleared ground, and from not having to compete with many or any surrounding plants. They are thus enabled to absorb whatever they require which the soil may contain. Fresh seeds are often brought from distant gardens, where the parent-plants have been subjected to different conditions. Cultivated plants like those in a state of nature frequently intercross, and will thus mingle their constitutional peculiarities. The crossed and self-fertilized plants were generally grown in pots in competition with one another, and always under as closely similar conditions as could be attained. They were grown in separate rows in the open ground. With several of the species, the crossed plants were again crossed, and the self-fertilized plants again self-fertilized, and thus successive generations were raised and measured.