ENDOSPERM OF UTRICULARIA 17 
together on a free central placenta and are tightly invested by 
the ovary wall. 
2. The female gametophyte, arising from the innermost 
megaspore, early digests the nucellus and protrudes from the 
ovule. It is never enclosed by the integument. 
3. This micropylar haustorium invades the tissue of the 
placenta which in anticipation of such intrusion has developed 
a mass of nutritive tissue opposite the micropyle of the ovule. 
4. The pollen tubes creeping down over the surface of the 
placenta encounter the protruding lobes of the female gameto- 
phyte, and pass through their cytoplasm to the synergids. 
5. Fertilization and double fertilization take place in prac- 
tically all of the ovules, few aborting at this early stage. The 
primary endosperm nucleus divides before union of egg and 
sperm is completed. 
6. The antipodals are very small and inconspicuous, and dis- 
appear soon after fertilization. 
_7. The endosperm early in its development pushes two cells 
past the feeble antipodals and develops a haustorium which 
penetrates to the epidermis of the ovule against which it flattens 
out. It persists until the seed is nearly mature and seems to 
take food from the heavy epidermal layer of the ovule. 
8. Similarly two endosperm nuclei pass by the egg appara- 
tus and enter the micropylar haustorium, which then energet- 
ically attacks the receptive tissue of the placenta. 
9. The funiculus of the ovule does not develop after fertili- 
zation, and rapid growth of other parts leaves it as a rudimen- 
tary structure which remains without vascular tissue and be- 
comes practically functionless. 
10. Within the dome shaped placenta vascular strands are 
freely developed with branches which end near the bases of the 
ovules. Each strand is directed towards the base of a funicu- 
lus, but terminates alongside the mass of ‘‘receptive’’ tissue. 
11. The micropylar haustorium remains prominent during 
seed development, digests most of the receptive tissue, and be- 
comes the medium through which food is transferred to the em- 
bryo. Adjacent cells of the placenta are elongated radially and 
seem to conduct food to the haustorium. 
12. The seeds during later development are practically with- 
