494 Camillo Karl Schneider: Morphologie der Gewebe (Anatomie). [68 



After a minute and careful study of the vascular system of the orders 

 now dealt with, I am prepared to affirm without much hesitancy that the 

 inverted cortical bundles of Calycanthaceae (allied as this order is to the two 

 others immediately concerned) are nothing more than the homologues of the 

 inverted bundles above described which occur in the cortex of Paeonia and 

 Magnoliaceae, and which represent portions of the ventral half of the petiole- 

 cylinder. Instead of, as in the case of lianitnculaceae, Magnoliaceae and 

 Paeoniaceae, these ventral bundles either uniting with the dorsal Strands of 

 the leaf-.cylinder or dying out in the internode of the stem, two of them from 

 each leaf persist in an enlarged form as independent cortical bundles in the 

 stem, never passing into the central cylinder. In the cortex of the peduncle, 

 however, concentric bundles occur, and we may interpret them morphologically 

 as being due to incomplete fusion between the dorsal and ventral bundles of 

 the leaf-cjdinder. 



Throughout these various orders we find the different phylogenetic 

 stages stereotyped in the actual structure of present-day species. This is 

 especially well seen in the Anonaceae. In Artabotrys, Polyalthia and Uvaria 

 we see a primitive structure extending through the greater part of the leaf, 

 their basis only showing the more modified, advanced structure; in Monoäora, 

 the structure which occurs only in the basal region of the leaf of Uvaria is 

 here typical for the organ as whole, indicating a greater advancement for the 

 genus; the arc-shaped contour of the lateral bundles in this plant (Monoäora) 

 represent in the ontogeny a congenital fixation of that stage in the phylogeny 

 in which a bündle from the ventral side is in the act of uniting with a bündle 

 of the dorsal arc; in other orders, viz, Ranunculaceae and Magnoliaceae, we 

 see this process actually taking place in the ontogeny; in Anoriaceae and 

 Paeoniaceae the process is no longer seen in actual Operation, but certain 

 stages of it have become fixed and arise congenitally as such in the individual 

 life-history. Eupomatia represent the most advanced type of this order in 

 which an ordinary arc of bundles extends throughout the leaf. The concentric 

 bundles which occur in the leaf of this order are homologous with those 

 which occur in the cortex of the stem of Magnoliaceae and Paeonia which is 

 only another instance of the fact that a given structure which in one group 

 of plants is found only in the leaf, may in another occupy that part of the 

 stem which is a direct continuation of the leaf; this Supports my view of 

 the origin of the cortical bundles of Calycanthaceae and also the phyton theory. 



125. Zijlstra, K. Die Gestalt der Markstrahlen im sekundären 

 Holze. (Rec. Trav. Bot. Neerl., V, 1908, p. 17—50, eine Textfig., 3 Taf.) 



Das Resümee lautet: 



1. Die kleineren Markstrahlen zeigen in allen untersuchten Fällen eine 

 Höhenzunahme nach dem Cambium zu. 



2. Es treten in den kleinen Markstrahlen oft Unterbrechungen durch 

 schieflaufende Faserschichten auf, die sich bisweilen weit in radialer 

 Richtung fortsetzen. 



3. Anfänglich nur durch wenige Fasern getrennte kleine Markstrahlen, die 

 gerade übereinander stehen, können weiter nach dem Cambium zu ganz 

 verschmelzen und sodann einen einzigen Markstrahl darstellen. 



4 Es konnte kein Zusammenhang konstatiert werden zwischen den Ver- 

 änderungen in der Höhe der kleinen Markstrahlen und in der Länge 

 der Libriformfasern von Querem Robur L. 



