73 
fruit. Thinning out of the blossoms results in the production of 
a good yield of fruits for two reasons — firstly there are fewer 
fruits to be supplied with food material, and secondly a great 
deal of energy has been saved by the loss of the thinned-out 
blossoms. 
STRUCTURE. 
On digging down it is found that long underground 
stems run out from the Christmas Tree, sometimes for 
great distances (one at Como was traced for 120 yards), and 
giving off aerial branches having the appearance of trees at in- 
tervals along their length. Small plants, which tnight be taken 
for seedlings, are frequently found in belts of country where the 
Christmas Tree is common and almost invariably these are found 
to be suckers from this long stem. The production of suckers 
explains why Nuytsia is so common throughout the South-West in 
spite of its extremely small production of fertile seeds. 
The growth of the stem is peculiar both microscopically and 
mac rosco pica 1 ly, the second peculiarity following from I lie first. 
A very noticeable character is the extreme brittleness of the 
branches and roots, quite thick members snapping under quite a 
small pressure. This is not the case with the young twigs of one 
year’s growth. It only takes place after secondary growth, and 
the explanation lies in the unusual and remarkable method of 
secondary growth of the tree. This is similar in both stem and 
root, when allowance has been made for their difference in primary 
structure. 
In transverse section the young stem is quite normal. (Fig, 
1. (A).) 
The central zone of pith is surrounded by the vas- 
cular bundles and these again by the cortex. In the normal 
dicotyledonous stem the cambium between the xylem and phloem 
elements divides forming xylem elements on the inner side and 
phloem elements on the outer side. In this way a cylinder of 
wood surrounded by phloem and cortex is produced. Jn the 
Christmas Tree the mode of growth is at first normal. There is a 
meristernatie layer between wood and phloem of the primary 
bundles and this divides until they have reached a certain size, 
when it loses its function and a new cambium is formed in the 
thin-walled cells of the inner cortex. This cambium is not con- 
tinuous round the stem but occurs in patches several cells in width. 
The cortex is divided into two fairly definite layers, the cells of 
the inner layer being thinner-walled and its cells smaller and 
more compact than those of the outer. When the new cambium 
is formed, several of these cells start to divide at different points 
round the stem forming typical cambium cells, 
