251 



This brings one to ask : — What variation in amount of a constituent, or what 

 constituent must be present or absent in any particular case to constitute a valid 

 species ? 



Classification on oils alone associates dissimilar species. 



We should reflect when we find it stated that the oils from E. bicolor, 

 A. Cunn., are similar to those attributed to "E. bicolor," and which are really the 

 product of E. Bosistoana, F.v.M. If this should be founded on fact, then it proves 

 that species with different genetic relationships resemble each other in oil-constituents. 



The classification based on oils alone places certain species and their varieties 



in different groups, e.g. — 



E. sideroxylon, A. Cunn. 



E. Stuartiana, F.v.M. 



E. tereticornis, Sm. 



E. rostrata, Schlecht. 



It also brings together species which perhaps every other classification shows 

 us do not exhibit close affinity. Instances of this can be quoted at any time. 



To sum up, I think that characters based on the essential oils are subject to 

 variation. They do not escape the interacting laws of change any more than 

 morphological characters do. 



Explanation of Plates (37-10). 

 PLATE 37. 



E. capitellata, Srn. 



1. Fruits (misplaced by White) of E. capitellata in White's "Voyage," 1790, p. 226, of the " Peppermint 

 Tree." 



2a. Leaf ; 26, pointed operculum and flowers of a specimen from Dr. (J. E.) Smith, ex herb. Lambert in 

 herb. Cant. Piece of the type of the species. 



3a. Leaf ; 36, buds, of R. Brown's E. congesta from Port Jackson. 



4a. Pair of juvenile leaves ; 46, pair of leaves in the alternate stage, showing the orbicular shape. 

 From Middle Harbour, Port Jackson. 



5(7. Buds ; 56, anthers ; 5c, fruits, from Oatley, George's River, a few miles south of Port Jackson. 



6a. Leaf ; 66, buds ; 6c and 6d, fruits. All from the same tree, North Shore, Port Jackson. Note the 

 variation in the amount of exsertion of the valves, and the similarity of 6a" to 1. 



[N.B. — All the above are practically identical.] 



la. Buds ; 76, fruits, from Guy Fawkes, New England. 



8a. Juvenile leaves in the alternate stage ; 86, mature leaf ; 8c, buds ; So", fruits of E. capitellata, var. (?) 

 latifolia, Benth. (B.F1. hi, 206). Portland, Vic, J. G. Robertson, 1842. 



9a. Leaf; 96, buds; 9c, fruits of E. santalifolia var. Baxleri, Benth. Portland, Vic, J. G. Robertson, 1842. 



10a, Leaf, with buds attached ; 106, fruits of E. capitellata. Portland, Vic. Mr. Adams, through A. E. 

 Kitson, 1904. 



11a. Leaf and buds ; 116, fruits. Sandy rises, Narracoorte, South Australia (W. Gill, 5/01). 



12a. Leaf; 126, rugose buds, simulating E. alpina ; 12c, fruits, Grampians, Victoria, 2,000 feet. (H. B. 

 Williamson.) 



