Abstract
The morphological changes in relation to chromosome doubling were discussed, especially on size and number of stomata in 7 species (Table 1) of tetraploid forest trees which were induced by colchicine treatments in the spring of 1942.
(1) Generally speaking, stoma size increases and stoma number decreases according to the chromosome doubling in the same individual, but forest trees show greatindividual variation, so it is not safe to compare the morphological changes in a small number of different individuals.
(2) When chromosome doubling is confined to epidermis or tetraploid sector, it cannot be concluded by only morphological changes whether the tree is totally tetraploid or not.
(3) Moreover, it may be considered that large stomata will be found at the leaves of first year's growth in the treated seedligs, but will become small according to acclimation as the years go by.
From the above, it is clear that size and number of stomata are helpful in a preliminary survey of polyploidy, but are not its absolute indices.
