554 
H. V. WILSON 
already contracted. It was partly covered by a pore membrane 
at the margin of which lay a nucleus. The marginal pore mem- 
brane was then largely drawn into the epidermis, the nucleus shift- 
ing its position in what remained (comp. sketches drawn at 1.50 
and 1.53). At 1.53 the marginal membrane began to spread 
rapidly, closing in the pore by 1.57. After complete closure of 
the pore the outline of the pore canal was still distinguishable. 
The outline was distinguishable but smaller at 2 p.m. The 
wall at this time was far from sharp and appeared rough and gran- 
ular, whereas before closure of the pore it was sharp and smooth. 
The rough outline at 2 p. m. probably indicates how far the mesen- 
chymal jelly has spread towards the middle of the original pore 
canal. 
Pore Jf. The pore at 2.05 p.m. was wide open, and at the mar- 
gin two nuclei were distinguishable (fig. 15, 2.05 p. m.). One 
nucleus, a, remains at rest, but the other nucleus, h, shifts its posi- 
tion back and forth in the usual way. Its position at successive 
moments is shown in the camera sketches made at 2.07 and 2.10. 
Nucleus h is the pore nucleus, the movements of which are associ- 
ated with the formation of the pore membrane. The other nu- 
cleus a is not especially concerned in the closure of the pore. At 
2.12 the epidermis has just crept beyond the margin of the pore, 
carrying with it the nucleus h. By 2.15 the pore membrane has 
completely crossed the pore and the outline of the pore canal is 
indistinguishable. 
Pore 5. At the beginning of the observations (fig. 16, 3.15 p.m.) 
the pore which is somewhat constricted is crossed by a single 
strand of protoplasm. The strand moves across the pore and in- 
corporates the nucleus (3.20). The strand with the nucleus at its 
base now shifts its position across the pore back and forth, finally 
passing to the edge and becoming a marginal film (3.30). This 
quickl}^ spreads ov^er the pore in the usual way. 
Pseudopodial activity at the pores 
While making observations on the closure of pores, pseudopo- 
dial activity was occasionally observed at the margin of the pore 
