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SUMMARY OF CURRENT RESEARCHES RELATING TO 
wood and a scanty cortex. “ The cambium which gives rise to the 
secondary bundles, the secondary cortex and part of the primary cortex 
between these two zones of secondary growth, are also visible to the 
naked eye.” The primary bundles are of two types ; one type is 
normal, but in the other type the phloem becomes disorganized and 
almost disappears ; the tracheids and vessels become clogged ; the cells 
surrounding the xylem exhibit vigorous meristematic activity, which 
continues until eight rows of cells have been formed and then ceases. 
The secondary tissues arise from cambium of pericyclic origin ; the 
bundles have scanty phloem, and companion-cells are rare, but there is 
no degeneration of tissues or clogging of the tracheids ; the surrounding 
cells show no meristematic activity. There is no cambium between the 
xylem and phloem such as is found in the primary bundles of many 
monocotyledons. The xylem cells are only slightly thickened, but are 
extremely hard. The growth-rings form the most striking part of the 
stem ; both their origin and irregularities appear to be due to climatic 
conditions. Similar, but less distinct, rings are found in A. pleuridens. 
The writer suggests that the previous failure to find growth-rings in 
woody monocotyledons may be due to the artificial conditions under 
which the plants examined have been grown. S. G. 
Oil-ducts in Eucalyptus and Angophora. — M. B. Welch {Proc. 
Linn. Soc. New South Wales , 1921, 46 , 475-86, 2 pis., 7 figs.). An 
account of the discovery of oil-ducts in certain species of Eucalyptus 
and Angophora. The details were studied in E. corymbosa , and it was 
found that the leaves and stems contain oil-ducts which are formed by 
the union of short secretory cavities. They are not continuous, and 
there is no direct connexion between them and the glands in the leaves, 
petioles or stems, but they correspond in size and formation, and they 
appear to secrete oil of a similar nature. They vary in diameter from 
0*03 to 3 mm., and in length from 1 to 100 mm., and apparently act as 
storage-reservoirs. They have not yet been found in the roots nor in 
the lower parts of the stems of seedlings. The discovery of these ducts 
in the Corymbosae class of Eucalyptus and in Angophora is important 
from an evolutionary standpoint, and confirms the theory put forward 
by Baker and Smith as to the common ancestry of these two genera. 
It seems probable that the species examined represent the oldest members 
of the genus, and that later types have lost these structures during the 
evolution of isobilateral leaves and a more oblique leaf -venation. 
S. G. 
Eucalyptus Oil-glands. — M. B. Welch (Journ. and Proc. Roy. Soc. 
New South Wales , 1920, 54 , 208-17, 4 pis., 1 fig.). An account of the 
structure and contents of the oil-glands of Eucalyptus. These glands 
occur in almost every species, but they vary in number, reaching a 
maximum in such types as E. polybractea and E. costata, and a minimum 
in E. terminalis. They are found in the leaves, petioles, young stems, 
calyx, operculum, and even in the fruits ; they rarely occur in the bark, 
but E. Bridgesiana and E. Macarthuri are exceptions in this respect. 
It is possible to make a rough classification of certain differences in 
arrangement of these glands which is chacteristic of different species ; 
