ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 543 



striking resemblance to the hypocotyledonary expansion of various 

 Helobiae. It is probable that the broad two-lobed expansion in the 

 Nelumbo embryo, commonly known as the cotyledons, is a true hypo- 

 cotyledonary body, bearing a rather close resemblance to the hypocoty- 

 ledonary expansion of Phyllospadix. The first leaf of Nelumbo then 

 becomes homologous with the so-called cotyledon in Buppia and 

 Phyllospadix. 



Jacket Layer in Sassafras.* — J. H. Schaffner describes a jacket of 

 cells surrounding the mature embryo-sac in Sassafras. It shows some 

 resemblance to the delicate zone in Agrostemma, but there is no distinct 

 limiting wall on the outside. It is from one to several layers of cells 

 thick, and behaves differently to stains from the outer layer. The cells 

 have large vacuoles, and comparatively little protoplasm, and begin to 

 degenerate when the embryo-sac is fully formed. It thus serves not 

 only to nourish the developing gametophyte, but by its disintegration 

 supplies food to the developing endosperm and embryo. This jacket 

 layer is a purely physiological tissue developed in various ways in 

 different angiosperms. It may be absent, as in Sagittaria and Lilium ; 

 represented by disintegrating cells in contact with the embryo-sac, as in 

 many monocotyledons and dicotyledons ; it may be developed, as in the 

 examples just discussed ; or it may be a highly-specialised layer of dark 

 staining cells, as in Aster Novce-anglice, described by Chamberlain. 



Overton, J. B. — Tiber Parthenogenesis bei Thalictrum purpurascens. (On parthe- 

 nogenesis in Thalictrum purpurascens.) 



[Gives cy tological details of the phenomenon, a general account of which was 

 given by the same author in 1902). 



Ber. Deuttch. Bot. Gesell, xxii. (1904) pp. 274-83 (1 pi.). 



Robertson, C. — The structure of flowers and the mode of pollination of the primi- 

 tive angiosperms. 



[Suggests that the primitive angiosperms were entomophilous, and that the 

 anemophilous ones are metamorphosed entomophilous flowers whose 

 seemingly simple structures are degraded, not primitive.] 



Bot. Gazette, xxxvii. (1904) pp. 294-8. 



Vogler, Paul — Die Variation der Blutenteile von Ranunculus Ficaria L. (Varia- 

 tion of the parts of the flower of B. Ficaria.) 



[The petals and the sporophylls show a marked parallel variation ; there is 

 no obvious compensation.] 



Vierttljalirsclti-. Naturf. Gesell. in Zurich, xlviii. (1904) 

 pp. 321-8, with explanatory curves. 



Physiology. 

 Nutrition and Growth. 



Assimilation of Atmospheric Nitrogen.-f-— Charlotte Ternetz finds 

 associated with the roots of Calluna, Erica carnea, Oxycoccus and Vacci- 

 nium a fungus which can assimilate atmospheric nitrogen. The fungus 

 has a much-branched septate mycelium, and forms brown pycnidia, which 



* Ohio Naturalist, iv. (1904) pp. 192-3 (fig. in text). 



t Ber. Deutsch. Bot. Gesell., xxii. (1904) pp. 267-74(1 pi.). 



