42 president's address. 



though there may be unmistakable indications of it. Fig. 3 of PI. iv., and lig. 5 of 

 PI. vi., show the damping effect of the presence of good pinniB e.xcellently. 



Fig-s. 1-4 of PI. vi., sbow the retarding influence of the presence of pinnse on 

 the flattening, in the leaves with the ma.ximum number of. pairs of pinna", that I 

 have succeeded in landing. These are very instructive. Leaves with 7-9 pairs 

 are not shown, only for want of space, and because they do not show anything 

 more than these do. 



Plate vii. shows the last stages of the decadent pinn<e, correlated with a 

 maximum of flattening of the leaf-axis. Figs. 1, 2. 4 and 6, rei)resenting the 

 pinnae on their last leg-s, are the only ones of the entire series wliich lack the 

 apical pair of pinnse. Figs. 4 and 5 are particularly instructive, because they 

 show a minimum amount of flattening in the proximal part of the leat-axis, where 

 the forlorn surviving pinn® or leaflets are stranded ; and then, distad of them, the 

 flattening soon increases. Fig. 4 has but two single pinnie with a reduced number 

 of leaflets ; unfortunately the upper portion of the euphyllode was missing when I 

 got it. Fig. 6 shows the lowest pair, and the one next above, represented by 

 leaflets; and then, altove these, a pair of reduced pinnae, and a distal better pair. 

 The portion of the axis below the lowest leaflet, the real or apparent petiole, is 

 longer than the internode above it — even allowing that it may be the real petiole — 

 but it is relatively very, short. In the face of such evidence as this, can anyone 

 still believe that the so-called phyllodes of the Australian Acacias are merely flat- 

 tened leafstalks or petioles which have lost their blades'? 



An interesting paper by Dr. C. E. Preston, on "Peculiar Stages of Foliage 

 in tiie Genus Acacia," is contained in the American Naturalist, Vol. xxxvi., p. 

 727, September, 1902. This is worth attention, because what is so often tacitly 

 assumed and taken for granted, is discussed in this jjaper; namely, to which pair 

 of leaflets of the fii'st simply pinnate leaf of a seedling does the single pair of 

 pinnae of the next bipinnate leaf correspond? Preston says: "A peculiar tran- 

 sition-stage between the singly pinnate and the bii)innate is sometimes found in 

 seedlings of A. leprosa Sieber, when growing under cultivation. The shadow- 

 prints (Figs. 1 and 2) annexed sliow the nature of this peculiarity. The lower 

 pair of leaflets only is replaced by a pair of strongly developed jiinna-, while the 

 rest of the axis runs on singly i)iimate and rather weak in structure. As a I'ule, 

 no such continuation of the main axis is to be found." Shadow-prints of two 

 young seedlings are given, showing an '"abnormal third leaf" in each ease; the 

 first being simply pinnate, the second bipinnate, and the third apparently tripin- 

 nate. With all due deference to the author, and simply on the ba.sis of nia/jna 

 est i-eritcix et preraleat, T venture to express the ojiinion that, having inadcquats 

 material, he completely missed the significance of his abnormal leaves, and mis- 

 interi^reted them . 



From my standpoint, tlii'V arc one of two thing's — (1 ) cither exani]des of 

 tripinnate leaves, an apical pair together with a terminal pinna (the middle one) ; 

 or, what is more probable, a complete, apical pair (the middle one, and one of the 

 lateral ones), and an incomplete |iair next below (the other lateral one. its fellow, 

 missing), the internode which should have separated the pairs (complete or in- 

 complete) not having lengthened. One cannot decide which view is correct, be- 

 cause the terminal seta is not mentioned ; and it is not recognisable in the small 

 shadow-prints. In lioth cases, the stalk l)elow the three pinnae is the common 

 petiole or primary leaf-axis, and not the petiole only, as the author suiiposos; as 

 is suggested by the length of it. 



Tambagc has examined seedlings of more species than ;iny other writer; 

 descrii)tions and illustrations of fifty-five have already been published. He has 

 not so far found a leaf of a seedling with the terminal pinna present, but he has 



