INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 905 



naceae, Compositfe, &c., or whether the septa appear only at a later 

 period, as in Eanunculacete. 



From these considerations, the mature embryo-sac may be 

 classified under four types : — 



1. Embryo-sac consisting of two special mother-cells ; two 

 tetrads ; antij)odals without anticlinals (Fluviales, lianunculacesB, 

 Cruciferfe, &c.). 



2. Embryo-sac consisting of three or four special mother-cells; 

 two or more tetrads ; antipodals ; one or two inert anticlinals (the 

 greater part of the Liliacea^ and allied families; Euphorbiaceae, 

 Papaveraceee, Rosaceas, Caprifoliace83, &c.), 



3. Embryo-sac consisting of three or four special mother-cells ; 

 a single tetrad ; no antipodals ; one or two inert anticlinals (Ona- 

 grariaceae, Saxifragaceas, Boraginaceae ; Primulaceae ; Apocynaceae ; 

 Compositfe, &c.). 



4. Embryo-sac consisting of four or five special mother-cells ; a 

 single tetrad ; no antipodals ; one or two active anticlinals ; an inert 

 or cotyloid anticlinal (Aristolochiacefe, Santalaceae, Scrophulariaceae, 

 Labiatae, Ericaceae, &c.J. 



Angiosperms and GjTimosperins.* — Professor Strasburger has 

 supplemented his previous researches on this subject by a publication 

 of great imjjortance. Owing to a change of view as to the homology 

 of the ovule in Gymnosperms, the terms for the two great classes 

 previously suggested, by him, Archisperms and Metasperms, are now 

 abandoned. The main results at which he has arrived may be 

 summed up as follows : — 



The points which have specially engaged the author's attention are 

 the development and homology of the ovule in Angiosperms and 

 Gymnosperms ; the origin of the embryo-sac, and the processes that 

 take place in it before impregnation ; the formation of endosperm ; the 

 structure, development, and homologies of the flower and inflorescence 

 in Gymnosperms ; and some questions as to fertilization and the 

 formation of the embryo in the same class. He is able to confirm his 

 previous observations on the development of the embryo-sac and the 

 jirocesses which take place in it in the case of Monotropa and the 

 Orchidefe, and considers them to be of general application. He dis- 

 putes Warming's and Vesque's j statement that the two or four cells 

 formed by the septation of the mother-cell of the embryo-sac ever 

 coalesce into a single cavity ; it is only one of these cells, usually the 

 lowermost, that develops into the embryo-sac, pressing aside its sister- 

 cells. The germinal apparatus and the antipodal cells are formed in 

 the same way in the embryo-sac ; there is never any formation of 

 tetrads in the sister-cells. Strasburger also disputes Vesque's assertion 

 that antipodal cells are not formed in many Gamopetalae. These asser- 

 tions are illustrated and proved by a large number of drawings. The 

 author does not agree with the view of Warming and Vesque that the 

 cells formed by the division of the mother-cell of the embryo-sac are 



* 'Die Angiospermen und die Gymnospermeii,' von E. Strasburger, Jena, 

 1879; sec 'B>t. Zeit.,' xsxvii. (1879) p. 514. 



t See this Journal, ante, p. 90-1. 



