562 Allgemeines. — Anatomie. 



des Schlittens von dem einen Schenkel eines am Schlitten be- 

 v/eglich befestigten Winkelhebels mitgenommen wird. Da die 

 Stärke der Hebung von der Stellung des Hebels abhängig ist, 

 so wird diese durch einen Sperrhaken regulirt, der am Block 

 befestigt ist und auf eine Skala am zweiten Schenkel des Hebels 

 eingestellt wird. Die Stellung des Messers wird durch 2 Schrau- 

 ben in der Messerklemme bestimm.t. Ferner zeichnet sich das 

 Mikrotom durch einen Tropfkessel aus, der die Beträufelung 

 des xMessers mit Alkohol gestattet. Zum Schluss weist Verf. 

 auf ein Messer hin, welches bei der Anfertigung gerader Schnitt- 

 bänder von Vorteil ist. Freund (Halle a. S.). 



ChäNDLER, S. E., On the Arrangement of the Vascular 

 Strands in the „Seedlings of certain Leptospo- 

 rangiate Ferns". (Ann. of Bot. Vol. XIX. 1905. No. 75. 

 p. 365.) 

 A description of the anatomy of the young plants of some 

 twenty different Ferns mostly belonging to the Polypodiaceae. 

 Attention is paid in particular to the manner in which the 

 vascular System of the roots passes over into that of the mature 

 stem. The account given of Pulypodium aureiim includes also 

 the structure of the mature plant, The author finds that in this 

 plant the first two ieaf-traces of the „seedling" arise from the 

 tvvo ends of a curved solid protostele without forming definite 

 leaf-gaps. The departure of the third leaf-trace breaks the 

 curved protostele directly into two separate Strands. A some- 

 what similar phenomenon is also described in Nephrodlum 

 hirtipes where the trace of the very first leaf consists of two 

 separate Strands which depart from the two ends of a curved 

 protostele as in Polypod'iiim aureiim. 



In referring to the Osmundaceae the author concludes that 

 the internal endodermis discovered by Faull in 0. cinnamo- 

 mea will be found to arise as a necessary accompaniment of 

 a typical ground-tissue pocket through a leaf-gap differentiated 

 early in the life of the plant. This pocket has, in all proba- 

 bility, „persisted" through successive internodes, and is only 

 occasionally in continuity with the external ground-tissue at the 

 gaps. 



Among other conclusions arrived at the author holds that 

 in dealing with questions of a so-called stelar character, we 

 must confine our attention to tissues of two categories only, 

 viz. vascular and non-vascular. Again, the primitive type of 

 vascular System in the ferns is a rod of vascular tissue with a 

 solid central xylem surrounded by phlocm, or the xylem has the 

 form of a ring surrounding a central mass of phloem. The complex 

 dictyotelic structure results from the moulding and elaboration 

 of this solid vascular Strand owing to the necessity for an ef- 

 ficient attachment of the Ieaf-traces, and the differeniiation of 

 ground-tissue pockets plays an important part in such elabo- 

 ration. D. J. Gwynne-Vaughan. 



