Notes . 
370 
transverse, while occasionally a sieve-plate may be seen in a lateral- 
wall near the end of a segment. The segments are very variable 
in length, some being equal to about six cambiform cells while others 
do not exceed the length of one of these. 
A radial section through the peripheral sclerenchymatous band, 
already referred to (along line AB), just where it passes out into the 
sclerotic sheath, shows about two rows of cambial cells, then from 
seven to nine sieve-tubes with their companion-cells. These abut 
directly on the crushed protophloem-band ( cr ) of the cortical bundle. 
When a radial section is made through the wood, as the latter projects 
into the phloem-mass, there seems to be a larger number of cam- 
biform elements here, and the number of sieve-tubes is often reduced 
to four or five. 
In the part of the section between the bundle and the 
phloem can be seen first, a number of large parenchymatous cells, 
then sometimes a band of sclerotic cells, or of fibres, and occasionally 
narrow bands of crushed elements. These bands also pass in a very 
interrupted line round the bundle-ring between the cortical bundles. 
In the phloem itself can be seen a mass of parenchyma with one 
to four sieve-tubes. Their course here is far more regular than it 
appears to be in tangential section. 
Sections were cut at points between the cortical bundles, but it 
was not found that sieve-tubes in the normal phloem were more 
numerous here than opposite the cortical bundles. 
It thus appears that the greater part of the sieve-tube system of the 
stem is located in the cortical bundles. This fact makes the structure 
and development of these bundles still more interesting. 
J. LLOYD WILLIAMS. 
Royal College of Science, London. 
THE INFLUENCE OF LIGHT ON DIASTASE L — It was 
shown by Brown and Morris in their researches on the physiology 
of foliage-leaves that the amount of diastase that can be extracted 
from foliage-leaves varies considerably in the course of twenty- four 
hours, being greatest after a period of darkness and relatively less 
after long illumination. 
Marshall Ward has shown again that the solar rays exercise a very 
1 Abstract of a paper read before the British Association at Oxford, August 1894. 
