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1898] EMBRYOLOGY OF ALYSSUM 319 
toward the suspensor by a series of transverse divisions, which 
at first apparently occur in acropetal order ( fig. 75), but later 
stages seem to indicate intercalary division (figs. 22, 23). The 
number of cells is variable, some large embryos having only 
eight- or nine-celled suspensors, while in others the number of 
cells reaches fifteen. In a few cases, instead of the normal 
transverse division in the suspensor cells, a longitudinal division 
occurs, giving a peculiar abnormal appearance (jigs. 22, 26, 
and 27) 
The function of the suspensor seems to be that of an absorb- 
ing organ, supplying nourishment to the rapidly growing embryo 
and serving the purpose of the root in mature plants. When 
stained with anilin-safranin or its combinations, the suspensor 
and the cells arising from the basal embryo cell stained much 
less deeply than those derived from the terminal embryo cell. 
This was of great advantage in clearly determining the origin of 
calyptrogen, root cap, and root tip. 
The suspensor persists until the embryo is mature, although 
it becomes shriveled and apparently functionless some time 
before the resting period of the embryo is attained. 
ENDOSPERM. 
The definitive nucleus divides immediately after the formation 
of the oospore: The endosperm accumulates very rapidly in the 
region of the proembryo and often obscures it, especially in the 
early stages. Early in my work I concluded that endosperm 
was formed previous to fertilization, because I frequently found 
it when I could not distinguish any embryo, But later research 
showed that endosperm was not present until after the proem- 
bryo appeared; and, whenever found, remains of a badly sectioned 
embryo were evident. Several instances in which. unfertilized 
oospheres were found in the same silicle with well developed 
embryos showed the definitive nucleus distinct and undivided in 
the shriveled embryo sac, and an entire absence of endosperm. 
The endosperm forms a complete lining for the embryo sac 
(fig. 12), and a passing through the well-known radiations, 
