172 Physiologie der Zellen, Gewebe und Organe. 



This is the first of a series of anatomical studies on this primitive group 

 of ferns. Gates (London). 



508) Takeda, H., Some points in the anatomy of the leaf of Welwit- 

 scliia mirahilis. In: Annais of Botany, Bd. 27, S. 347 — 357, PL 29, figs. 5, 

 1913. 



Various features of the leaf of this peculiar plant, such as the epidermis, 

 stomata and vascular tissue, are described. The leaves exhibit many typical Gym- 

 nospermic characters and especially show a close relationship to the other mem- 

 bers of the Gnetales. The phloem is of the Gymnospermic type, there being no 

 companion cells. The writer considers Welivitschia and the rest of the Gnetales 

 as Gymnosperms, and favors the hypothesis that the Gnetales have a closer re- 

 lationship to the Cycads than to the Conifers. Gates (London). 



509) Hill, T. G. and De Frame, E., A consideration of the facts rela- 

 ting to the structure of seedlings. In: Annais of Botany, Bd. 27, S. 257 

 bis 272, 1913. 



This paper contains some of the general conclusions of the authors from 

 their extensive work on seedling anatomy. The many difficulties in using the 

 anatomy of seedlings as a basis for phylogenetic conclusions are pointed out, and 

 the importance of the physiological considerations — "the influence of physio- 

 logical necessity on morphological expression"' — is emphasized. 



It is considered that the diarch rather than the tetrarch structure wslS pro- 

 bably the primitive one in Angiosperms, for it is the commonest type in Gymno- 

 sperms and is universal in the primary root of modern Pteridophytes. The evo- 

 lution of seedling anatomy would then be in the direction of increasing, rather 

 than diminishing complexity as has frequently been supposed. 



Physiologically there is a close relation between the size and water-carrying 

 capacity of the vascular tissue, and the amount of food material in the cotyledons 

 which is to undergo hydrolysis. In other seedlings, as Fagus sylvaüca, where the 

 cotyledons soon take on a photosynthetic function, the same mechanical require- 

 ments for a water-supply oblain. In seedlings of this plant an almost perfect 

 curve was obtained, showing the close relation§hip between the surface of the 

 expanded cotyledons and the area of a cross-section of the bundles. The size of 

 the seedling is very important, as Comp ton has also found, and tetrarchy appears 

 to be characteristic of large seedlings while diarchy is found in small ones. Thus 

 in the Cactaceae, the species witli large seedlings have typically a tetrarch root, 

 while those with small seedlings have a diarch root. Gates (London). 



Hierzu: Nr. 493, 49Ü, 504, 506, 525, 537—539, 540, 545, 54G, 548, 558, 570, 592, 627. 



/ 



Physiologie der Zellen, Gewebe und Organe. 



510) Gräfe, Yiklor, Einführung in die Biochemie für Naturhistoriker 

 und Mediziner. Leipzig und Wien (Fr. Deuticke) 1913. 472 S. 41 Abb. 

 Ji 13,—. 



Die Biochemie hat in den letzten Jahrzehnten bedeutsame Fortschritte ge- 

 macht und sich besonders in der Tier- und Pflanzenphysiologie zu einem Haupt- 

 zweige entwickelt. Zahlreiche Lehrbücher sind eine Folge dieser Entwicklung 

 gewesen. Es ist dabei für jeden Autor erforderlich seinem Werke eine besondere 



