C)) A. BARBER. 5 
noted in our study of Santalum album (Sant. II, Plate V> 
fig. 2): 
4. In the next stage of development considerable differ- 
entiation of tissues has taken place (Plate II, fig. 1). The sec- 
tions were mounted in dilute glycerine, and it is thus possible 
to study the cell contents more carefully. The first point of 
importance is the presence of a well-marked hypodermal layer 
(a). This is characteristic of Cansjera haustoria. Starch, 
although sometimes present here, is hidden by dense granular 
contents which in later stages assume the form of oily (?) drops. 
Immediately within the hypoderm the cortex (f) becomes 
early cleared of contents and the deeper, starch-laden cells 
(g) are arranged much as in the earlier stages of the Olax haus- 
torium (Olax, Plate III, fig. 2). The densest part of the shadow 
of starch grains is met with outside the upper part of the 
nucleus, and the tissues become clearer along the lines of growth 
towards the host’s root. The lines of growth are well defined 
and the cortex is distinctly separable from the nucleus. The 
development of the vascular system is, as usual, the vessels 
in the transitional region appearing long before those lower 
down. A downward extension of the vascular system is also 
commencing on each side of the nucleus, the cells of these 
procambial strands being’ densely filled with protoplasm and 
actively dividing by longitudinal walls (c). 
The upper limit of the nucleus is clearly shown at this 
early stage, in this respect differing markedly from the hausto- 
rium of Olax. The cells immediately above the nucleus (6), 
really ground tissue and therefore of a similar origin to those 
of the cortex, but separated from it by the procambial strands, 
have become elongated tangentially and form a distinct mass 
of tissue. The cells of the nucleus, on the other hand, remafn 
at first isodiametrical and divide rapidly in all directions (d). 
In the lower part of the nucleus a median strand of tissue 
is traceable, the contents of whose cells become applied to 
their walls, giving them an appearance of thickening (e), This 
