102 GOTE TURESSON 
nably satisfactory, such a statement is not warranted with regard to 
the ecospecies. 
In the efforts made by the writer to arrive at an understanding 
of the Linnean species from an ecological point of view — of the 
ecospecies, as I prefer to say in the following — studies have been 
made of a number of plant species. Usually species with extensive 
distribution, each occurring in as many different localities as possible, 
have been selected. The conditions in the natural habitats have been 
noted as far as possible, and seeds and pieces of turf have been collec- 
ted and brought home from various habitats in order that the types 
might be followed in permanent cultures laid out in the experimental 
fields. A review at this stage of some of the results of these studies 
is intended to show the necessity and importance of a comparative 
study of organisms in their natural habitats and in the experimental 
field when the question of the differentiation of species and varieties 
is to be discussed. 
It is much to the purpose to start with certain species belonging 
to the genus Atriplex, which have been in my cultures since 1916. 
Several species of this genus grow abundantly along the Swedish 
coast. One of these species characterized by thick, fleshy, rhombic- 
lanceolate leaves, and flowering earlier than any other of our species 
grows all along the coast in the zone nearest to the water. Sets of 
seeds and small plants of this species have been collected from some 
thirty different localities and cultivated. A remarkable hereditary va- 
riation has been found to occur. The distribution of these varieties 
in nature offers, however, a most interesting study. It is found that 
the eastern coast strip is inhabited by a certain group of types di- 
stinctly different from the population inhabiting the rest of the coast 
(fig. 1). This group of types has been described under the specific 
name Atriplex praecox by HüLpHers (in Lınpman, 1918). If the spe- 
cies is examined on the west coast, we find that the coast farthest 
to the south, the marshy coast strip along the Sound, is inhabited by 
types which in the fruiting stage are easily seen to be quite different 
from other types of the species but which during the flowering period 
closely resemble the eastern representative. Types of this southern 
group were described as long ago as 1838 by Dreser (1838) under the 
»species», i. e. homozygotic biotypes. Since there is already in existence an older 
and well-established term, which covers this conception, viz. JOHANNSEN’S pure 
line, no valid objection can be raised to the use of the term genospecies in the 
sense given to it in the above. 
