BY J. J. FLETCHER AXD C. T. MUSSON. 226 



the encircling tumour, and that the former are situated over the 

 latter. 



In an adult Mallee, the shoots and the stem, if present, are 

 all approximately the same height, and diameter. But in the 

 seedling shown in PI. xxi., fig.3, the seedling-stem has so far 

 maintained its initial lead. There must be some intermediate 

 stage, therefore, when the shoots are able to overhaul the stem. 

 Possibly this may come about when the lateral, water-storing 

 roots are sufficietjtly developed, to supply more water in the 

 aggregate, than the taproot alone is able to do. Such questions 

 as these cannot be profitably discussed without satisfactory 

 material, and observation on Scrub plants. 



F. Mueller, Maiden, and Cambage, and others, have recorded 

 instances of Eucalypts of species which are ordinarily Mallees, 

 sometimes being trees; but we have failed to find any explana- 

 tion of such cases. From our point of view, it is not difficult to 

 understand that infection may fail to take place occasionally, or 

 that, from accidental causes, or because the individuals were re- 

 fractory, it may have been followed by little in the way of results. 



The root-waterstoring arrangements of Eucalypts, whether 

 Mallees or not, as well as of other Australian plants, in arid 

 regions, are in need of scientific investigation. Little is known 

 of this important subject, beyond what explorers, travellers, and 

 early colonists gleaned from the Blacks, and have put on record. 

 Naturally the Blacks chose the roots of the big Mallees. 

 But it is a reasonable supposition, in the absence of scientific 

 evidence, that the smaller VVhipstick Mallees also stored water, 

 though not on a scale sufficient for the -Blacks to attempt to 

 exploit it. Inferentially, all the Mallees must have water-storing 

 roots, otherwise it is inexplicable how the tumours of the Mallees 

 can keep their shoots, and persist. 



Eucalypts may have water-storing roots, however, without 

 being Mallees. The only author who mentions this fact, that 

 we are aware of, is K. H. Bennett. In his description of the 

 method of obtaining water from Eucalypt roots, as practised by 

 the Aborigines of the arid country between the Lachlan and 

 Darling Rivers,* he says "The Eucalypti consist of a gum (the 



* These Proceedings, 1883, viii., p. 214. 



