66 SUMMARY OF CURRENT RESEARCHES RELATING TO 



occur laterally situated with respect to the outgoing leaf-traces, and 

 these have been misinterpreted as foliar lacunae. The same applies 

 to the more modern species of Sigillariae. 



Nature of the Tracheae in Ferns.* — D. T. Gwynne-Vaughan, 

 having examined the xylem of some of the recent ferus, has come to the 

 conclusion that the xylem elements of the Pteridophyta are, for the most 

 part, vessels with true perforations in their longitudinal as well as in 

 their terminal walls ; that in the Osmundacefe, NephroiMum filix-mas, 

 and probably others, a special type of vessel occurs which is characterised 

 by the complete disappearance of the primary tracheal wall at certain 

 points, so that the cavities of the pits are vertically continuous in the 

 middle of the wall. It is probable that more or less rounded pits pre- 

 ceded the transversely elongated pits of the scalariform type in the 

 Filicales. 



Vascular System of the Filicinese.j — A. G. Tansley brings to an 

 end the publication of his lectures on the evolution of the filicinean 

 vascular system. In Lecture ix. he makes a general survey of the 

 leaf-trace in the Filicineas, the comparative treatment of which subject 

 we owe to Bertrand and Cornaille and to Gwynne-Vaughan. The rest 

 of the lecture is concerned with the ontogeny of the filicinean vascular 

 system. In Lecture x., Tansley makes a comparison of the vascular 

 system of the ferns with that of other phyla of vascular plants, compares 

 the morphological construction of Selaginella with that of other ferns, 

 and finally gives a brief comparison of the ferns with the Cycadofilices 

 which lead up to the Cycadophyta and the flowering plants. A glossary 

 is appended to define the principal terms employed in these lectures, 

 relating to the construction of the stelar system. Titles of 37 works are 

 given in the bibliography. 



Sporangiophore in the Pteridophyta.:}: — M. Benson passes under 

 review the different types of sporangiophore found among the Pterido- 

 phytes, fossil and living. She discusses the morphological value of the 

 sporangiophore, and concludes as follows : — On the whole, a review of 

 the great central phylum, Pteridophyta, as a group of plants derived 

 from a common ancestor, whose sporophyte generation bore a special 

 type of asexual spore-producing organ called a sporangiophore, seems 

 illuminating and possibly useful as tending to concentrate attention on 

 the probable origin of the structure in question. 



Cavity Parenchyma and Tyloses in Ferns. § — M. McNicol gives a 

 resume of what has been written about cavity parenchyma and tyloses 

 found in contact with the protoxylem groups in the petioles of some 

 ferns, and describes what she has herself observed of this tissue in a 

 number .of ferns, for example, in Mkrolepia, Pteris, Alsophila, Dickson ia, 

 Cibotium, Marsilia, and others. In discussing its function, she says that 

 cavity parenchyma is to be regarded as a special tissue formed by the 



* Ann. of Bot., xxii. (1908) pp. 517-23 (1 pi.). 



f New Phytolog., vii. (1908) pp. 1-16, 29-40 (figs.). 



% Tom. cit., pp. 143-9 (figs.). 



§ Ann. of Bot., xxii. (1908) pp. 401-13 (1 pi.). 



