402 
body of the chlorophyll-grain and the exceedingly delicate mem- — 
brane, the white projections being the optical sections of the 
elevated ridges which give the surface its pitted aspect. 
In fig. 3 is shown an isolated chromatophore in optical sec- 
tion after treatment with alcohol, by which the grain has shrunk, 
while a few of the ridges have become rather more prominent, the 
outline here representing the surrounding membrane, the space 
between, in the microscopical specimen, being black. 
If such a microscopically broad space of darkness is an optical 
illusion, I am at a loss to account for it on any optical principle 
with which Iam familar. If it isan optical illusion, why the upper 
margin of the black band should slope from the long projection 
near the upper right-hand border of the chloroplast to the mi- ; 
nutely projecting point at the very apex of that corner, and form © — 
concavities between succeeding elevations, becomes even more 
inexplicable. The enveloping membrane exists. 
In addition to the membrane there is a coating of the cell-pro- 
toplasm in which each chlorophyll-grain is imbedded. Yet each : 
chloroplast is not entirely isolated from all the others, but is inti- 
mately connected by the peculiar arrangement of the protoplasm, ' 
which does not entirely fill the cell as it frequently does in similar 
bodies, but forms a kind of protoplasmic cobweb which loosely ~ 
fills each cell with its delicate threads. It is these protoplasmic ue 
threads which connect together the chromatophores, and it ap” : 
pears to be by their contractions that the position of the gree® 
bodies is changed under the influence of the light. A somewhat — 
similar arrangement of the protoplasm has been observed in Sela- 
ginella by Haberlandt ;* a part of one . his drawings is —— in 
fig. I. ; 
In Astrophyllum these protoplasmic threads are colorless, vary 
ously branched and in continuous movement. Every eae 
phore in the cell is connected by their means with every o 
_and the threads themselves radiate from the nucleus. | 
In fig. 5 are shown several leaf-cells with the: protoplasmic 
threads extending across and around, some being in the mae 
tral parts of the cell and therefore having no chromatophores - 
_ their course. These delicate filaments are 2 oS quivering; 
'* Flora, 90: 221.- 
* 
: 
4 
