25^4 Phylogenie der Coniferen. 



Der Hauptunterschied zwischen beiden Gruppen liegt aber darin, daß 

 bei den Pineen ein ausgiebiges System anastomosierender Harzkanäle 

 vorkommt, während dieses den Äbietineen abgeht oder nur in den Kegeln 

 vorkommt, welche, wie so viele Reproduktionsorgane, ancestrale Merk- 

 male am längsten beibehalten. So alternieren z. B. bei gewissen 

 CatowzYes - Fruktifikationen die Gefäßbündel nachfolgender Internodien 

 nicht, also wie im Stamme von Archeocalamites, während sie dies in 

 den vegetativen Teilen tun. 



In dieser Reduktion der Harzkanäle erblickt Jeffrey nun einen 

 Fortschritt und betrachtet deswegen die Äbietineen in seinem Sinne als 

 eine Gruppe, welche von Pineen herzuleiten ist. Darüber sagt er: 



If we attempt to picture to ourselves the probable course of evo- 

 lution, which has led to the more or less complete loss of the resiu- 

 canals in the Äbietineae [as defined above] it would appear to be as 

 foUows. The ancestral forms provided with a comprehensive and freely 

 anastomosing system of resin canals in both cortical and ligneous 

 tissues, were thus safeguarded against infection in case of injury, but 

 at great cost both in the large supply of resinous secretion necessary 

 to supply the needs of this extensive system, and in the large quan- 

 tity expended in sterilizing a wound. On account of the reduced foliage 

 of even the Abietinous Conifers, this was a very serious drain on the 

 assimilatory apparatus. Gradually the more economical tendency arose 

 of forming resin passages in the case of need only. In Pinus this 

 tendency is scarcely observable, while in the other three genera of 

 the Pineae it has become quite marked. In the Äbietineae it has passed 

 beyond the stage even of a marked tendency and has become the rule, 

 so that in this subfamily the original extensive and anastomosing system 

 of resin canals has become reduced to isolated and uncommuuicating 

 ducts, quite useless as a rule from the protective standpoint and per- 

 sisting as ancestral relics in the more conservative organs and parts 

 of the plant. The place of this system is taken by the much less costly 

 expedient of resin cells and by traumatic resin ducts which are formed 

 in the case of need only. 



Diametral entgegengesetzter Meinung in seinen Auffassungen über 

 die phylogenetische Bedeutung zusammenhängender Harzkanäle ist 

 Penhallow; in seinem Buche: North American Gymnosperms, Boston 

 1907, p. 150 sagt er: 



„If our Interpretation of observed facts is correct, as applied to 

 the origin of the resin passages it shows as clearly as one could well 

 expect a progressive development from the isolated resin cell through 

 various phases of aggregation to the highest form of structure (anasto- 

 mosierende Harzkanäle) as found in Pinus.^' 



Weiter sagt er, daß, falls man Jeffreys Meinung akzeptieren 

 wollte: It would, first of all, necessitate a direct reversal of the 

 structural sequence and this in turn would impose the necessity of 

 placing the genus Pinus at the bottom of the scale, while those 

 genera, like Taxus, Torreya, Dammara etc. which have no resin cells 

 even, would be at the top. I venture to suggest such a proposition 

 would meet with instant Opposition, even from the advocates of the 

 idea, that the resin passage has preceeded the other forms of resin- 

 bearing structures." 



