736 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the two divisions, and have been at some pains to bring together the 

 various views on this subject. At present, however, it does not seem 

 possible to come to any definite conclusion. But whether the group be 

 mono- or di-phyletic, and if monophyletic whether dicotyledons or 

 monocotyledons be the older, there can be no question that the two 

 divisions are naturally and intimately associated. " The characters that 

 separate them .... are cumulative rather than specific," and in a 

 morphological account, such as the present, their separation would involve 

 useless repetition. Hence the subject-matter is not arranged, as in the 

 case of the Gymnosperm volume, according to families, but the sub- 

 division is a morphological one. 



The chapters treat in succession of the flower, the micro- and mega- 

 sporangium, the female and male gametophyte, fertilisation, the endo- 

 sperm, and the embryo. Then follow chapters on the classification of 

 the monocotyledons and of the two great groups of dicotyledons (Archi- 

 chlamydere and Sympetalas), the geographic distribution of Angiosperms, 

 fossil Angiosperms, and the phytogeny of Angiosperms. Finally, Prof. 

 E. C. Jeffrey contributes two chapters on the comparative anatomy 

 of the Gymnosperms and their allies and on the comparative anatomy of 

 Angiosperms. 



The book supplies an excellent and much-needed presentation of the 

 subjects treated, and the full references to literature which are given at 

 the end of each chapter show the student where to go for further 

 information. 



The figures, many of which are original, are both plentiful and good. 



Development of the Ovule in Casuarina.* — H. 0. Juel has ampli- 

 fied and amended in a few details Treub's account of the ovule in this 

 genus. The most important point of his work is the observation of a 

 tetrad division of the embryo-sac mother-cells, the first nuclear division 

 being of a heterotype nature and showing a reduction of chromosomes. 



Formation of the Egg and Division of an Antipodal Cell in 

 the Juncacese.f — M. Laurent finds that the embryo-sac of the Juncacere 

 shows the normal arrangement of eight nuclei. The two synergids 

 disappear before fertilisation ; the two polar nuclei were not observed 

 to fuse. At the approach of fertilisation the median antipodal cell 

 becomes very conspicuous, advances towards the exterior of the sac, and 

 occupies a corresponding position to the egg-cell at the micropylar end ; 

 it stains more strongly than the two lateral antipodal cells which remain 

 small. The author was unable to induce the germination of the pollen 

 tetrads in a damp chamber, either in pure water or in different sugar 

 solutions, but they germinated readily in water in the presence of the 

 stigma. Pollination is direct in several species of Juncus, especially in 

 J. Bufonius where the flowers are always cleistogamic. In Luzula prot- 

 andry in universal. 



After fertilisation the two lateral antipodals soon disappear, but the 

 median grows considerably : its nucleus divides into several unequal 

 daughter nuclei ; these again divide and form a nucleated area of highly 



* Flora, xcii. (1903) pp. 284-93 (1 pi.). 



f Comptes Eendus, cxxxvii. (1903) pp. 499-500. 



