ON TIJE EMBRYO-SAC IN AXGIOSPERUS. 519 



of the Himalaya, Lebanon, the Taurus, and Algeria were races 

 of one formerly more generally distributed tree, and that their 

 isolation was due to geographical and climatal changes in the area 

 over which the species was distributed. Under this point of view 

 it becomes very important to determine to which of the known 

 races of Cedar that of Cyprus most nearly approaches : this can 

 only be satisfactorily done on the arrival of ripe cones and seeds, 

 which I am assured I shall receive very shortly. Meanwhile I 

 may state that, in size of cone, and size, form, and colour of leaf, 

 the Cyprus approaches the Algerian far more closely than it does 

 any Taurian, Himalayan, or Lebanon Cedar. 



A Contribution to our Knowledge of the Efhbryo-Sac in 



Angiosperms. By H. Marshall "Ward, B.A., Scholar 

 of Christ's Coll., Cambridge. (Communicated by "W. T. 



This elton Dyer.) 



[Bead November 20, 1879.] 

 (Plates XVII.-XXV.) 



Preliminary Remarks*. 



Being engaged during the past summer in an investigationf 

 concerning the origin of the embryo-sac in Angiosperms, the 

 paper by Vesquc, in Ann. d. Sc. Nat. 1878, naturally came under 

 consideration. I there found, among others, drawings of the 

 embryo-sac in Butomus with which my own by no means agreed ; 

 and on pursuing the matter further, I drew up the following 

 account and drawings in the form of a paper, that is now laid 

 before the Society in the hope that it may serve to throw some 

 light on the important question of the morphological signification 

 of the ovule and embryo-sac. 



On pursuing the investigation, and extending observations to 

 other plants, it appeared possible that the structure of the ovule 

 in Butomus might turn out to be a key to the understanding of 

 what occurs in other ovules — that some common law of growth 



The general method followed in the preparation of the microscopic speci- 

 mens in the present research has been to treat fresh ovaries with absolute 

 alcohol, afterwards adding glycerine, and therein retain for some hours. 



t Most of the work in this paper was done at Kew, in the " Jodrell La- 

 boratory." 





