in Myzodendron punctulatum , Banks et Sol . 1 99 
In Thesium the embryo-sac is described as stationary until 
after fertilisation, then, but for a short distance only, its anti- 
podal end grows backwards in the placental pillar, as seen in 
Hofmeister’s figures : — * Its lower portion remains during the 
whole further development of the seed a simple cell [italics 
mine]. Its lower end elongates to a long-drawn tube which, 
after perforation of the tissue of the ovule, curves vertically 
downwards and penetrates deep into the tissue of the ovu- 
liferous column ’ (T. X. F. 3-6). Speaking of Griffith’s work 
on the Santalaceae , Hofmeister says, ‘ The development of the 
seed of Osyris seems, from the little we know of it from 
Griffith, to be quite like that of Thesium . The embryo-sac 
grows out forwards from the nucellus, and extends to the 
base of the same.’ Schacht’s investigation of Santalum album 1 
was mainly directed to a determination of the egg-apparatus 
and of the connection in fertilisation between the pollen-tube 
and the synergidae as now known, the naked apical end of the 
embryo-sac being very favourable for this examination. Myzo- 
dendron agrees with Thesium in the outgrowth of the syner- 
gidal end of the embryo-sac into the ovarian cavity after 
fertilisation, as a result of the formation of the endosperm. In 
this particular point Myzodendron and Thesium are distinct 
from Santalum and Osyris , in which the apical part of the 
embryo is a long, naked, projecting tube before fertilisation. 
Looking at Santalum and Osyris , it would seem as if the 
forward upward growth of the sac was the result of a tendency 
of the sac to grow to meet the descending pollen-tube, much 
as the ovum in some animals sends out pseudopodia to meet 
approaching spermatozoa. This explanation of the pheno- 
menon will scarcely apply to the case of Myzodendron and of 
Thesium , in which the embryo-sac before fertilisation, in so far 
as it is enclosed by the nucellus, is normal. It may be that in 
all the genera named the protrusion is due to the minuteness 
of the ovules, the necessity for plenty of room for the develop- 
ment of the seed, and for the absence of pressure in the early 
stages of the same. 
1 Schacht, in Pringsheim’s Jahrbucher, iv, p, i, t. 1-4. 
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