410 



Taking all the readings, the angles in the lowest third vary from 15 to 55 degrees, 

 with the majority below 40 degrees. 



The middle third varies from 30 to 50 degrees, the majority being between 

 35 to 45 degrees. 



The top third varies from 30 to 55 degrees, average 40 to 50 degrees. 



The angles of the lowest and top thirds are here less constant than those of the 

 middle thirds. 



E. corymbosa (four leaves examined). 











Lowest Third 



75-85° 



70-75° 



75-80° 



65-70° 



Middle „ 



60-70° 



60-65° 



65-70° 



55-65° 



Top „ 



50-55° 



50-60° 



50-65° 



50-55° 



The angles here diminish as they go higher up the leaves. 



E. paniculata (three leaves examined). 



Lowest Third 50-60° 45-50° 40° 



Middle „ 45-50° 40-45° 40° 



Top „ 45-50° 40° 40° 



Other leaves show less difference in the three sections, while other show differences 

 chiefly at the extreme ends, e.g., E. Andreivsi. 



Oil Glands. 



Don (" Dichlamydeous Plants," ii, p. 818, 1832) in a very few cases refers to 

 Eucalyptus leaves as " full of pellucid dots " or gives some brief reference to dots. 



It is, of course, in oil-bearing leaves, an indication, even a quantitative 

 indication, of the presence of oils, but it is so common in the genus that most writers 

 ignore record of the oil-dots unless they are especially abundant. 



In the present work I have an occasional note on the subject, e.g., under 

 E. stellulata, at Part V. p. 128, under E. incrassata, Part IV, p. 98, under E. Morrisii, 

 Part XXXII, p. 56. 



Prof. G. Briosi has published an important paper, under the auspices of the 

 Botanical Institute of the University of Pavia (under the title " Intorno alia anatomia 

 delle Foglie dell' Eucalyptus globulus Labill.," Milan, 1891, with 23 plates). It is 

 a quarto work of 95 pages, and is probably the most exhaustive work ever published 

 in regard to the anatomy of the leaves of a single species of Eucalyptus. (The account 

 of the oil glands is of especial interest.) 



" Oils are the more volatile constituents of complex mixtures, secreted by glands of various forms, 

 whose solid constituents, after the oils have been driven off, are resins. These secretions may escape at 

 once upon the surface, or they may be stored in intercellular receptacles and released only by crushing. 

 Even in very small amounts, they may be distilled, and when more abundant they may be expressed and 

 purified." (Coulter, Barnes and CowleB' " Text Book of Botany," I, 413.) 



