204 tumours of eucalypts and angophoras, 



Non-Mallee Eucalypts. 



Seedlings of some species of Eucalypts are exempt from 

 tumours. We have met with six of these, referred to later on. 

 As mentioned in our introductory remarks, tumours, which 

 accomplish all they can do, pass through the three stages of — 

 (1) axillary, shoot bearing stem-nodules; (2) composite, shoot- 

 bearing, stem-encircling tumours; and (3) composite, stem-encir- 

 cling, shoot-bearing, root-incorporating tumours. 



Axillary Stem-nodules. — Five young seedlings, with one or 

 more pairs of stem-nodules, with the cotyledons, or some of the 

 leaves in situ, are shown in Plate iv. The cotyledons and lowest 

 leaves have usually disappeared by the time the nodules become 

 recognisable, as in the two series of seedlings shown in Plate v. 

 When they are absent, therefore, it is to be understood that the 

 opposite and distichous arrangement of the nodul^-s corresponds 

 to a similar arrangement of the cotelydons and leaves, in whose 

 axils the nodules develof ed. Figs. Al and A2 are seedlings of 

 E. corymbosa, each of which has only one pair of nodules. Both 

 nodules of the older one have a shoot with several pairs of leaves. 

 Older seedlings of this species are shown in Plate xi. Figs. Bl, 

 B2, and B3 are seedlings of E. hemiphloia, one with two, and 

 two with four pairs of stem-nodules. These supplement the 

 series of the upper row of Plate v.; they are shown here simplj^ 

 because they happen to have one or several leaves in situ. 



The upper row of Plate v. shows a gradational series of five 

 voung seedlings of F. hemi])hloia not old enough to show more 

 than three pairs of nodules. The three youngest (from right to 

 left) show the successive development of one, two, and three 

 pairs of axillary nodules. The first pair of the second seedling- 

 have made good progress, and are obviously more advanced, that 

 is older, than the second pair. This is not so evident in the 

 third seedling, which has a bend in the axis. The fourth ex- 

 ample shows a further advance. The nodules of the first pair 

 have grown unequally, so that one is bigger than the other, 

 though of the same age; while fusion between them has made 

 some progress. The second and third pairs have made fair 

 progress. The fifth example shows still further advance. 



