SECTIONAL TRANSACTIONS.— K. 387 



Dr. Adrianck S. Foster. — Nodal Anatomy and the Morphology of Bud- 

 scales in Dicotyledons. 



One might be led to believe, from the confident opinions expressed in many 

 botanical texts, that the morphological nature of bud-scales had been definitely 

 settled, and hence no longer constituted a problem demanding further investigation. 

 However, a careful survey made by the writer of the extensive literature on the 

 subject, especially of the contributions of German and French investigators, indicated 

 that sufficient differences of opinion have prevailed in the past, and indeed still exist, 

 to warrant a complete re-examination of the problem with particular regard to the 

 hitherto neglected evidence furnished by nodal anatomy. 



The results and general conclusions drawn from the writer's investigation of the 

 nodal anatomy of the bud-scales of about 130 species of ligneous Dicotyledons may 

 be briefly summarised as follows : — 



(1) Nodal anatomy furnishes an important clue to the specific homologies of bud- 

 scales, especially in plants where these organs have been regarded equivalent to 

 modified stipules or to ' fused ' leaves. 



(2) In the majority of the species investigated, the nodal anatomy of the bud- 

 scales and foliage-leaves is identical. 



(3) With few exceptions, the stele of the axillary bud of the scale or leaf is 

 associated with the gap of the median trace, a fact of great assistance in the interpre- 

 tation of specialised nodal conditions in the bud. 



(4) Two types of nodal specialisation have been found, viz. : — 



(a) The reduced node (confined to tri- and multi-lacunar species), where the 



scale receives fewer traces than the foliage leaf. Reduction involves either 

 the suppression of one or more of the lateral traces, or, in stipulate leaved 

 species, the suppression of the median trace with the development of the 

 laterals. 



(b) The amplified node (found in uni-, tri- and multi-lacunar species), where the 



scale receives more traces than the foliage-leaf through the addition of 

 accessory lateral traces. 1 



(5) The reduced node is frequently (not always) associated with the small outer 

 scales of the bud, while the node of the inner scales usually simulates that of the 

 leaf. The amplified node is often found in buds with a small number of well-developed 

 scales, and seems to represent a higher degree of specialisation than the reduced node. 

 A study of the comparative ontogeny of scales and leaves may be expected to shed 

 light on the significance of these types of nodal specialisations. 



(6) The close parallelism between the node of the bud-scale and foliage-leaf 

 lends no support to the theories that scales are (a) organs sui generis, (b) vestiges of 

 the primitive foliar organs of the Angiosperms, or (c) developmental possibilities of 

 ' indifferent leaf-primordia.' On the contrary, the evidence from nodal anatomy, 

 together with corroborative data from ontogeny, experiment, histology, transitional 

 forms and teratology suggest that bud-scales probably represent the original ontogenetic 

 modifications of foliage-leaf primordia with subsequent evolutionary specialisation. 



(7) The fact that the nodal typography of the scale and leaf tends to be identical 

 in a given species is evidence of the similarity in the early developmental stages of 

 these organs, and emphasises the necessity for a specific, rather than a generalised, 

 interpretation of the particular homologies of bud-scales. 



Mr. A. E. S. McIntosh. — Perithecial Development in Nectria Mammoidea. 



The origin of the perithecium cannot be traced to any differentiated archicarp. 

 The perithecium is at first composed of a small knot of twisted hyphte, all of which 

 stain similarly. Later certain cells near the centre become differentiated and stain 

 more deeply, while others disintegrate. This results in the formation of a cavity 

 into which the differentiated cells protrude whip-like extensions. The central cavity 

 enlarges and there arises a differentiation of the deeply staining central cells into an 

 upper and lower group. The cells of the upper group by growth down into the cavity, 

 ultimately reach the foot and intertwine with those of the basal group ; these former 



1 Cf. Sinnott, E. W., ' Investigations on the Phylogeny of the Angiosperms,' I. 

 ' The Anatomy of the Node as an aid in the classification of Angiosperms.' — Amer. Jour. 

 Sot., I., 303-322, 1914. 



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