THE EMBRYO-SAC IN ANGIOSPEEMS. 541 



the embryonic vesicles and antipodes are homologues of spores 

 and pollen-grains ; the other cells, of which the nucleus does not 

 become divided, and to which I have given the name of c anti- 

 clines] are the homologues of special mother cells arrested in 

 their development." 



The resume on p. 262 contains an important modification of the 

 original statement*, and in some respects concedes in favour of 

 Strasburger's views. On p. 291 the author gives it as still his 

 opinion that the conjugation of the nuclei is an accidental pheno- 

 menon, and in no way sexual 



On p. 311 several important corrections to the original account 

 of Butomits are made, and may be compared with his figures and 

 those given with the present essay. In a footnote to the same 

 page Vesque has suggested a similar interpretation of the " first 

 division in the embryo-sac" to that already given by myself, and 

 hinted at in a recent paper f; and the corrections to his previous 

 account of Orchis may also be compared with what is said there. 



DESCRIPTION OF THE PLATES. 



N.B. Except where otherwise stated, the figures are generally drawn from 

 sections in alcohol and glycerine, examined under Zeiss J (imm.) ocs. 2 & 3. 

 The figs, on PL XVII. however, and figs. 1-3 on PI. XVIII. were under 

 Gundlach VII. (immersion). 



Plate XVII. 



Butomus umhcllaius. 



Fig. 1. Early rudiment of ovule as an emergence from the placenta. This and 



the next from fresh specimens treated with alkali. 



2. Optical section of older rudiment : an axial row of cells is established. 



3 & 4. Actual sections through older ovules, showing first subepidermal 

 divisions to form integument : in fig. 4 the " mother cell of embryo - 

 sac " is evident. 



5. More advanced ovule in longitudinal section. The second integument 



is rising, to follow upon the first ; and another series of tangential 

 divisions under the epidermis has made the nucellus broader. 



6. Similar stage looked upon from above ; the mother cell of embryo-sac 



is as yet undivided. 



7. Slightly older stage, treated with acetic acid &c. to show outlines : the 



ovule is nearly anatropous ; the nucellus contains a long embryo-sac 

 mother cell ; the tangential divisions extend forwards ; and radial walls 

 have cut up the nucellus into more numerous cells. The two integu- 

 ments are growing up rapidly over all. 



Ann. des Sci. Nat. 1878, p. 276. 



1880 



