146 Anatomie. — Morphologie, Befruchtung, Teratologie etc. 



the mycotrophic habit of life. Its retention in the specialised Gva- 

 mineae which are streng transpirers and contain no mycorhiza 

 would then be explained merely as hereditary trait. 



M. Wilson (Glasgow). 



Boodle, L. A. Lignification of the Phloem of Heliantlms- 

 (Annais of Botany. Vol. XX. 1906. p. 319—321). 



H. anniius, H. tuberosus, H. laetißorus and H. decapetalus were 

 examined. Lignification of the sieve-tubes and other phloem elements 

 was observed in all the above species. In H. aumtus the lignification 

 of the phloem begins immediately on the inner side of the scleren- 

 chymatous groups and proceeds towards the xylem; in the medullary 

 rays of the phloem it begins later and passes from within outwards, 

 Usually the pericycle in the Upper region of the stem becomes lig- 

 nified, the change beginning comparatively late and proceeding 

 tangentially from the sides of the sclerenchyma masses; it ceases 

 accurately at the endodermis. In one case where no cambium 

 remained a transverse section showed a mass of lignified tissue 

 consisting of the xylem and all the tissues between the latter and 

 the endodermis and interrupted only by small islands of unaltered 

 phloem. Lignification of the proteid contents of the sieve-tubes was 

 Seen in the roots of all the specimens. It occurred in sieve-tubes 

 where the callus formed a thick deposit on the sieve plates as well 

 as in others where the callus was absent; it extended throughout 

 the length of the tube or was only observed near the sieve-plate. It 

 is suggested that the lignification of the walls may possibly set in 

 near the time of the death of the elements and this may depend on 

 several factors affecting the supply and demand of food substances, 



M. Wilson (Glasgow). 



Ewapt, A. J. and A. J. Mason- Jones, The Formation of Red 

 Wood in Conifers. (Annais of Botany. Vol. XX. 1906. p. 201— 203. 

 With one plate). 



Stems of Piniis sp. and Cupressus sp. were forcibly bent into 

 circular or elliptical forms so that the geotropic and pressure effects 

 were not equally distributed, the former influencing the horizontal 

 portions whereas the compression was restricted to the inner surface 

 of the curves. Red wood was formed mainly on the under surfaces 

 whether they were subjected to pressure or tension but there was a 

 tendency for the formation to spread to the vertical regions; in one 

 case it occured on the upper inner surface of a main axis. 



The authors conclude that the formation of red wood is a mor- 

 phological response to a gravitational Stimulus which is able tu 

 spread longitudinally from the region where it is directly perceived 

 and which may, under special circumstances, be modified or sup- 

 pressed by very strong pressure Stimuli. M. Wilson (Glasgow). 



Benson, M., E. Sanday and E. Berridge, Contributions to 

 the Embryology ofthe Amentiferae. Pt. IL Carpimis Betulus. 

 (Transactions of the Linnaean Society. Vol VII. Pt. 3. 1906. p. 37—44. 

 With one plate.) 



The embryo-sacs, of which a considerable number may occur 

 in one nucellus, contain the normal polar groups of nuclei. They 



