22 BULLETIN 5 9, HAWAII EXPERIMENT STATION 
Considerable variation is evident in the foregoing table. Selection 
for large size of nut (samples Nos. 4 and 7) did not result in an 
increase in size of kernel, but in an increase in thickness of shell. 
Obviously, this method of selection is undesirable. 
In chemical, composition, the series may be divided into two 
groups : Samples Nos. 2, 3, and 4, with lower oil content but higher 
in carbohydrates and water than samples Nos. 1, 5, 6, and 7; and 
these last-named samples. That this grouping may have some sig- 
nificance is indicated by the fact that a number of persons to whom 
the samples were submitted pronounced the former group to be the 
superior in flavor. 
Sample No. 6, although a different variety from the others and 
undesirable as an edible nut, is similar in chemical composition to the 
other samples. 
SUMMARY 
On account of the growing interest in Macadamia-nut culture in 
Hawaii, an effort has been made to bring together the more perti- 
nent data on the subject and to place on record the results of investi- 
gations that have been in progress at the station for a number of 
years. 
The Macadamia nut (Macadwnia temifolia) is a native of Queens- 
land and New South Wales, Australia. It was introduced into 
Hawaii about 1892, when a few small plantings were made. These 
trees began to bear in 1908, and by 1910 considerable interest was 
aroused in the possibility of growing the nuts in commercial quan- 
tities. 
A description is given of the tree and the nuts, and suggestions are 
offered for the propagation of the trees. While the tree is usually 
grown from seed, methods of vegetative propagation are described 
whereby strains of superior merit may be extended. Rooted cuttings, 
air layerings, and grafting were all tested at the station,, and rooted 
cuttings and side-tongue grafting were found to be the most prac- 
ticable methods of vegetative propagation. 
The Macadamia is strictly a tropical tree and in Hawaii grows 
from sea level to an altitude of about 2,200 feet. While it is con- 
sidered to be a drought-resistant tree in Australia, it has done best 
in Hawaii where there is a rainfall of 30 inches or more or where 
irrigation is practiced during the drier part of the year. The tree 
does not appear to be limited to certain types of soil, although in its 
natural habitat the Macadamia is found in rather rich alluvial soils 
along creeks and rivers. Strong winds injure the tree, and it re- 
quires protection, especially while young. Windbreaks are con- 
sidered necessary in establishing orchards of Macadamia nuts in 
Hawaii. 
Directions are given for the planting of orchards and for the 
tillage, pruning, and training of the trees. 
Macadamia nuts rank with almonds, pecans, and walnuts in com- 
position, although there was found to be considerable range in the 
percentage of protein, fat, and total carbohydrates in lots of nuts 
from individual trees and from different localities. 
Macadamia-nut oil is said to compare favorably with the finest 
grade of edible olive oil and to have some medicinal value. It is 
thought that the oil could be used to make a high-grade soap and a 
