the author read the following paper on the conception "variety" .
Under the name variety, units of quite different order and sense are understood . An attempt is made to define the most important types .
2 . BOTANICAL DEFINITION
The variety is a group of plants agriculturally recognized as a unit . Anyone who is engaged in defining the concept "variety" is automatically compelled to seek a starting point in botanical classification . This classification terminates in the main in the species as the smallest unit . WETTSTEIN defines the species as : "the totality of individuals which correspond to each other and to their progeny in all properties which the observer considers essential ."
ABERG, whom I think I might name as an authority in the sphere of the classification of field crops, adopts the attitude that the species should not be a too narrowly restricted unit in the case of the cultivated plant . There should be scope therein for variation, and it must be sharply characterized by a small number of stable features which cannot be influenced by environment . As a unit of the second order, within the species, the varietas can then be distinguished and within this, as a unit of the third order, the forma or strain . Now ABERG does not wish to make an arrangement in which the term forma is used for a natural and spontaneously occurring variant, vis-a-vis strain to indicate a distinguishable unit created by human hands . He merely prefers to distinguish the varietas within the species and, within the former, the strain . What he designates as a strain conforms quite well to what is known in agricultural language as a "variety" . He therefore allots this "variety", under the designation "strain", a place in the botanical system as a unit of the third order within the species . These strains are often only differentiated from each other by minor distinctions.. Now environmental variations are so important in respect of these distinctions that study under divergent conditions is necessary to be able to give an essential differentiation .
He raises the problem of the most desirable name for this unit of the third order