642 Lewis.— The Life History of Grijfthsia Bornetiana . 
No. of 
cell . 
Tetrasporic and cystocarpic plants. 
A ntheridial plants. 
Apex. 
max. diam. 
min. diam. 
length. 
max. diam. 
min. diam. 
length. 
1 
•060 mm. 
•060 mm. 
•65 mm. 
•65 mm. 
2 
*130 
• 190 
•50 
-25 mm. 
1-25 
3 
.250 
•400 
.40 
•25 
1.25 
4 
•320 
•600 
•40 
.20 
1.25 
5 
• 320 
• 160 mm. 
1-000 
•45 
• 20 
1.50 
6 
•400 
•200 
I * I 5 
•45 
• 20 
2*00 
7 
•400 
• 200 
1.30 
•45 
• 20 
2.00 
8 
.400 
• 200 
1. 60 
•50 
.18 
2*25 
9 
•450 
• 160 
2 « 0 O 
•55 
.16 
2.5O 
10 
• 5 2 ° 
• 15 ° 
2.5O 
•60 
•15 
3 *°° 
15 
.580 
• 160 
3-20 
•60 
•15 
3-00 
20 
•640 
• 200 
2*50 
•65 
• 20 
2.5O 
The cell-wall responds to the usual tests for cellulose. After the 
death of the cell, the wall swells greatly in aqueous fluids. When so 
swollen, it shows a plainly lamellate structure (Fig. 5), similar to that 
described for Bornetia by Correns ( 19 ). 
The cytoplasm forms a thin layer over the inner face of the free 
portion of the cell-wall, averaging *6 fx in thickness in the older cells. On 
the cross-wall it forms a thickened circular pad ; adjoining pads are in com- 
munication through the intercellular pores. The cytoplasmic pad over the 
upper cross-wall averages in the larger cells 10 n in thickness in the centre, 
becoming thinner toward the edges. On the lower cross-wall the pad is 
usually thinner, averaging about 3/x in thickness. The pads are about 
evenly divided into a granular layer adjoining the sap-vacuole, and a denser 
homogeneous layer next the cross-wall (Fig. 6). Nuclei are quite abundant 
in the granular layer but are not of usual occurrence in the homogeneous 
portion of the pad. Spherical bodies of various sizes, probably of a proteid 
nature, occur commonly in both layers of the cytoplasm over the cross- walls. 
In Griffithsia barbata , Berthold ( 7 ) found the cytoplasm divided into a 
clear outer layer and a granular inner layer, the latter containing the nuclei 
and the chromatophores. This seems to be the usual arrangement of the 
protoplasmic elements in the coenocytes of algae. In Griffithsia Bornetiana 
the cytoplasm becomes plainly differentiated into two layers only where it 
reaches a considerable thickness, as in the thickened pads mentioned above, 
and in very young cells in which the sap-vacuole is still small. 
Intercellular connexions are conspicuous in living as in stained 
specimens by reason of the peculiar plugs which close the otherwise open 
pit between the cells. Griffithsia is an unusually favourable form in which 
to observe the intercellular connexions because of their large size. Evidence 
presented below is believed to be strongly in favour of the view, doubted 
by many workers, that even the older cells are actually in physical and 
organic connexion through the large open pores in the cross-walls. 
