484 OCCL'RREXCE OF OIL DUCTTS IN' CERTAIN EICALYPTS AND ANGOPHORAS. 



I.S.O., F.R.S., for his couitesy in allowing me to obtain material of many of 

 the rarer Euealypts from the Botanic Gardens. I am also indebted to Mr. R. 

 T. Baker, Professor Lawson and Dr. McLuckie for kindly advice and criticism 

 throughout the work. 



List of References. 

 BakJer, R. T., and Smith, H. G., 1920. — A research on the Euealypts, especially 



in regard to their Essential Oils, 1st Ed. 1902, 2nd Ed. 1920, Dept. of 



Education, N.S.W., Technical Education Series Nos. 13 and 24. 

 Bextham, 1866. — Flora Australiensis. Vol. 3. 

 Haberlanut. — Physiological Plant Anatomy. 

 Hall, C, 1914.— The Evolution of the Euealypts in relation to the Cotyledons 



and Seedlings. Proc. Linn. Soc. N.S. Wales, xxxix., 1914, p. 473. 

 Macaj^pine and Remfrey, 1891. — The transverse sections of Petioles of Euealypts 



as aids in the determination of species. Trans. Soy. Soc. Vic, ii., pt. 1, p. 1. 

 Smith, H. G.. 1914. — On the Essential Oils of the Angophoras. Proc. Boy. Soc. 



N.S.W., Vol. 47, 1913, p. 106. 

 SOLEREDER, 1908. — Systematic Anatomy of the Dicotyledons. English translation, 



Oxford. 

 Zimmerman. — Botanical Microtechnique. 



EXPLANATION OF PLATES XLII.-XLVI. 



Plate xlii. 



E. corymbosa Sm. Transverse section of a portion of a leaf showing typical 

 arrangement of the two central oil ducts in the medulla between the two parallel 

 bicollateral vascular bundles. The almost equal distribution of the xylem in 

 two bands along tlie greater portion of the leaf is typical of Euealypts of the 

 Corymbosae group. The palisade tissues are developed towards the upper sur- 

 face only in this species. 



Plate xliii. 



Fig. 1. X 55; Fig. 2. x 80; Fig. 3. x 110; Fig. 4. x 60; Fig. 5. x 70; 

 Fig, 6. s 50. 

 Fig. 1. 



E. macidala Hook. Transverse leaf sectit)n with two ducts, in which a 

 small dark residue remains. This section was made from dried material. 

 The palisade extends right across the lamina, and .stomata occur on either 

 surface. 

 Fig. 2. 



Angophora lanaeolata Cav. Transverse leaf section. This is the only genus of 

 the Myrtaceae, outside the Euealypts, in which central oil ducts have so far been 

 found. The xylem of the mid-rib in this species more nearly approaches that 

 found in tlie majority of Euealypts, thougli in some material there was a 

 tendency towards the E. corymbosa type. The contents of the ducts (normally 

 two) are liglit yellow in colour and soluble in 95-100 per cent, alcohol. As in 

 tho other Angophoras the palisade tissue is found towards the upper surface 

 only, though this is the only species of the genus in which ducts have so far 

 been observed. 

 Fig. 3. 



E. citriodora TTook. Transverse leaf section. Two ducts are usually found 

 in this species. The palisade tissues extend right across the leaf, and stomata 

 occur on both surfaces. 

 Fig. 4. 



E. calophylla R. Br. Transverse leaf section in which two ducts are present, 



