THE GENOTYPICAL RESPONSE OF THE PLANT 213 
part of the individual, or whether these forms are brought into exi- 
stence through a genotypical response of the species-population to de- 
finite habitat conditions. 
Before going into details I wish to express my gratitude for the 
help received from so many sources during my work. The nature 
of the work necessitated considerable space. Professor H. Nitsson- 
EuLe, head of this Institute, has not only put the resources of the 
institute at my disposal; but to him I am also indebted for much 
inspiring advice given freely during the progress of this study. The 
necessary green-house space as well as other facilities have been kindly 
provided for me by Professor S. MurBEck, head of the Botanial Mu- 
seum and Garden in Lund, who has taken much interest in my work. 
I also take this opportunity of acknowledging my indebtedness to Pro- 
fessor H. Kyrın, head of the Botanical Laboratory in Lund, for his 
kindness in promoting these studies in different ways. 
The collecting of the various plants in cultivation, discussed in 
the following, has been done chiefly by myself on journeys some of 
which have been rendered possible through economical support from 
the Physiographical Society and the Botanical Club of Lund. However, 
material of certain forms has also been supplied by friends interested 
in my work and to them I wish to extend my sincerest thanks for 
all their kindness. I am under obligation to Messrs. N. STENSSON, and 
K. B. KRISTOFFERSON, for the necessary photographic work. 
I. THE MATERIAL AND THE CULTURES. 
Transplantations on a small scale were begun in 1916. At that 
time isolations were also made of species of the genus Atriplex. The 
necessary ground for these cultures was obtained in my home garden 
in Malmo. With the increase in the number of cultivated species and 
in the number of individuals of each species the space became too 
small, and in 1918 the cultures were moved to the Institute of Genetics 
at Akarp. Since then the cultures have much increased; the area 
covered by individuals of perennials transplanted from various habitats 
is at present about 25 ares. The soil is a fine loam, and the con- 
ditions of the ground show satisfactory uniformity throughout. In 
order to maintain this uniformity no animal manure is used. The 
plants in the permanent cultures (that is the perennials) are planted 
in rows, usually with a distance of 40 cm. between the plants in the 
row and of 50 cm. between the rows. The more bulky ones are given 
