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INTRODUCTION TO EMBRYOLOGY OF ANGIOSPERMS 



basal cell cb does not divide but becomes greatly swollen and vesicu- 

 lar. The terminal cell ca divides diagonally into two unequal cells, 

 of which the larger cell cd becomes swollen like the basal cell. 

 These two haustorial cells, cb and cd, persist for a long time and 

 appear like synergids (Fig. 169 A-F). 



In Corydalis (Soueges, 1946a,o) the basal cell cb undergoes a num- 

 ber of free nuclear divisions and becomes multinucleate. The 

 terminal cell ca divides transversely to form a short filament, whose 

 upper cells (cd and cf) become large and multinucleate and con- 

 tribute to the suspensor. Only the apical cell takes part in the 

 development of the embryo proper (Fig. 1Q9G-L). 



ABC 



Fig. 168. Synergid-like suspensor cells of Myriophyllum altemiflorum. 

 after Soueges, 191,0; G, after Stolt, 1928.) 



(A-F, 



In the third genus Fumaria (Soueges, 1941a, b) the nuclear divi- 

 sions in cb are accompanied by wall formation. All the derivatives 

 of this cell, as well as the upper derivatives of ca, give rise to the 

 suspensor, the embryo proper being produced only from the lower 

 derivatives of ca. Thus, approximately three-fourths of the zygote 

 is given to the production of the suspensor (Fig. 1Q9M-R). 



Since the publication of Treub's (1879) classical paper on the 

 embryogeny of the orchids there have been several other investiga- 

 tions on the family, among which those of Stenar (1937, 1940) and 

 Swamy (1942a,6, 1943, 1946, 1948, 1949) deserve special mention. 

 It is noteworthy that while some genera like Epipactis, Lister a, 

 and Zeuxine completely lack a suspensor, others show a remarkable 

 variation in the form and organization of this organ, which may be 

 illustrated by the following examples. In Spathoglottis, Goodyera, 

 and Achroanlhes the basal cell of the proembryo enlarges and some- 

 times grows out of the micropyle. In Gymnadenia, Phajus, Epiden- 

 drum, and Habenaria it divides to form a filament of cells which 

 may frequently become very long and twisted and grow out as far as 



