MEMOIRS. 
On the Embryo-sac and Development of Gymnadenta 
CONOPSEA. By H. Marshall Ward, Scholar of Christ’s 
College, Cambridge. With Plates I, II, and III. 
The hitherto received account of the origin, mode of for- 
mation, and homologies of the embryo-sac in Angiosperms 
was based on the researches of Hofmeister,^ for the most 
part, and may be summed up to the following effect: — A 
single cell situated in the apical part of the nucleus, and 
usually the foremost of an axial row, enlarges, its nucleus 
disappears, and a variable small number of free nuclei 
appear in the protoplasm by free cell formation. Of these, 
two are close to the apex of the enlarged cell, and are 
known as germinal ” or embryonic ” vesicles, while a 
very inconstant number of antipodal ” cells often, but not 
always, forms in the lower end of the protoplasm. The 
enlarged cell is the embryo-sac, and receives the pollen tube 
at its apex, where one, or at times two, of the germinal vesi- 
cles become fertilised by the contents of the tube. Schacht^ 
showed that one of the germinal vesicles acted as a 
conductor between the tube and the fertile vesicle, or that 
two acted as such towards a third germinal vesicle, and 
were often marked by peculiar longitudinal striae. 
This ‘‘ filiform apparatus ” and fertile germinal vesicle 
were regarded as the homologues of the corpuscula^ of the 
Gymnosperms by Strasburger and Pringsheim, and therefore 
were regarded as representing rudimentary archegonia, in 
accordance with Hofmeister’s views as to the rosette ” or 
iieck-cellsin Conifers.'* The antipodal cells came to be regarded 
as the last and fleeting representatives of the endosperm, 
which arises in the embryo-sac of Coniferm, &c., and which 
* “Neuc Beitra^e,” &c., in ‘ Abliandluiig d. Kouigl. siiclis Gescllsch. d. 
AViss.,’ 1859 and 1801. 
‘Jahrb. f. Wiss, Bot./ 1857. 
® R. Brown (1834;), ‘ Misc. Bot. Works.’ 
* ‘ The Higher Cryptogams,’ Ray Soc., 1802. 
VOL. XX. NEW SEK. 
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