344 GÖTE TURESSON 
The species problem is thus seen to be in a large measure an 
ecological problem. As such it has- hitherto remained almost un- 
attacked from an experimental point of view. While at present the 
purely genetical side of the problem is fairly well understood, we have 
only to a slight extent been able to arrive at an understanding of the 
ecological questions involved. So much appears certain, however, that 
the Linnean species are units of the same importance ecologically as 
their constituent elements are genetically. In view of the necessity of 
keeping the distinction between ecological and purely genetical units 
ee Coenospecies 
- Ecospecies 
Syst ee Ecolype 
-- - -- Ecophene 
Fig. 78. 
in mind, the term ecospecies has been proposed (Turessox, 1922) to 
cover the Linnean species or genotype compounds as they are realized 
in nature. 
It is evident that we do not find realized in nature the whole 
possible range of combinations within such an ecospecies because of 
the control of living and non-living factors of the outer world. If the 
ecospecies be subjected to artificial crossing or withdrawn from the 
close control of some of these controlling factors, as is already ac- 
complished to a certain extent when the species is brought under 
culture by man, the great number of possible combinations within the 
ecospecies might be brought to light. Such an extension of the limits 
ordinarily set by nature might also, as is well known, be attained when 
