258 EMBRYOGENESIS IN PLANTS 



both into the endosperm and into the micropylar endosperm 

 haustorium (Carlson and Stuart, 1936). In some species the suspensor 

 cells show remarkable growth and development, sometimes into 

 haustorial structures. Among the Leguminosae, some species of which 

 have greatly reduced or no suspensors, Pisimi, Fig. 64d, and Orobus 

 have greatly elongated pairs of multinucleate, saccate, basal suspensor 

 cells. In Lupinus and Cicer, Fig. 64b, e, the suspensor is a very long, 

 enlarged, multicellular, filamentous structure. In L. pilosa some of the 

 more basal of these cells may become rounded off and lie detached 

 near the micropyle. Ononis, Fig. 64g, has a long filamentous suspensor, 

 the cells being full of food reserves. Phaseohis, Fig. 64c, has a massive 

 cylindrical embryo, without any sharp distinction between the suspensor 

 and embryo proper. This embryo affords a remarkable illustration of 

 an acropetal gradient of cell size. Cytisus, Fig. 64f, has a suspensor 

 consisting of a spherical aggregate of swollen spherical cells. Rau 

 (1953) has illustrated an embryo of Cwtalaria striata in which the 

 suspensor develops a large number of tubular cells which become 

 associated with the endosperm. 



Among the Rubiaceae the remarkable suspensor haustoria have 

 long been known. The suspensor is initially a filament of cells, but later 

 the most basal cells, next the micropyle, grow out as filamentous 

 structures which penetrate into the endosperm and become swollen at 

 their distal ends. Fig. 66. The haustorial function of these cells can 

 scarcely be doubted. Incidentally, they supply evidence of an indirect 

 kind that the embryo probably takes in its nutrients at the basal region 

 and translocates them to the distal formative region. Fagerlind (1937), 

 however, has indicated that these suspensor haustorial tubes may soon 

 become detached from the main body of the embryo, or they may soon 

 degenerate. 



In Myriophyllum (Halorrhagidaceae) the large basal cell divides by 

 a longitudinal wall and each of the two daughter cells becomes greatly 

 distended. Fig. 65, filling the micropylar end of the embryo sac. A 

 somewhat similar development is found in Hypecoum (Fumariaceae) 

 but here the basal cell, and the lower segment of the transversely 

 divided terminal cell, are involved. Corydalis has also an enlarged basal 

 cell, in this case with several free nuclei, while in Fumaria the basal cell 

 and some of the lower segments of the terminal cell develop into a 

 multicellular foot-like structure. Fig. 65. in Sedwu acre, and other 

 members of the Crassulaceae, the basal cell becomes greatly enlarged 

 and forms an aggressive haustorium, Fig. 64a, the branches of which 

 penetrate the integuments and even the seed coat. 



In Tropaeolum majus, the basal cells of the proembryo undergo 

 rapid relative growth, some of them giving rise to a long haustorial 



