146 ON THE INTERCELLULAR RELATIONS OF PROTOPLASTS. 
existence of open communication between neighbouring cells 
in the endosperm of the seeds of certain palms— Strychnos nux- 
vomica , Areca oleracea , and Phcenix dactylifera. As this 
investigation of Tangl’s, although describing what for some 
years appeared to be isolated phenomena, is still the starting 
point of recent research in this direction, we will give to it 
brief special attention. 
The endosperm of Strychnos nux-vomica is bounded out¬ 
wardly by layers of cells elongated at right angles to the 
surface, and therefore shown best in a section taken in this 
direction. The inner tissue of the endosperm, shown by 
sections taken parallel with the surface of the seed, and at 
some little distance below that surface, consists of thick 
walled cells, with strongly-swelling membranes. Under the 
influence even of water these membranes swell very greatly, 
and show strongly-marked lamination. If a dried section of 
this inner endosperm tissue is allowed to swell in dilute alcohol 
the lamination of the membrane is manifest, and at the same 
time a fine cross striation is seen in the walls of adjoining 
cells. But if a section of this same portion of the endosperm 
is treated with potassium iodide iodine, these stride stain 
yellow or brown, and show as “ fine threads penetrating the 
cell walls in their entire thickness” (see fig. 7).* For reasons 
derived from the relations of these strite towards colour 
re-agents, Tangl came to the conclusion that the striae were 
none other than delicate prolongations of the outer layer of the 
cell protoplasm penetrating the cell walls and communicating 
with one another. They are not visible in the dry state, nor 
in absolute alcohol, from the close relationship of their 
refractive index with that of the surrounding cell membrane. 
By absorption of water these refractive indices are changed in 
unlike degree, so that the threads show out in the laminated 
membrane with a greater or less degree of clearness, just as 
the lamination itself of the membrane shows for the same 
reason. 
The endosperm of Areca oleracea , examined by means of 
sections taken parallel with the surface of the seed, and 
swollen in water, shows walls of considerable thickness and 
homogeneous structure, with local thin areas, corresponding 
in position in adjoining cells, but presenting no structural 
peculiarities. If, however, similar sections are allowed to 
swell in chlorzinc iodine (“Schultz’s solution”) until the 
cell-walls have taken a uniform blue coloration, it will then 
* The figures illustrating this portion of the paper will be published 
in connection with a future instalment. 
