36 SCIENCE. 
of only slight staining capacity, which has 
often been called the grownd-substance. Dur- 
ing cell-division the meshwork in the 
neighborhood of the dividing nucleus as- 
sumes a radiating appearance, giving rise 
to the so-called asters, or astral systems 
which are typically double, forming the 
amphiaster (Fig. 8,6). We may define the 
Ore? 
Fic. 1. (a) Protoplasm of the egg of the sea-urchin 
( Toxopneustes) in section ;(b) protoplasm from a living 
star-fish egg (Asterias) ; (c) the same in a dying con- 
dition after crushing the egg ; (d) protoplasm from a 
young ovarian egg of the same. (All the figures 
magnified 1,200 diameters. ) 
problems suggested by these appearances 
by a series of questions as follows: 
1. What is the actual structure that gives 
the appearance of a meshwork ? 
2. How faithfully does the preserved 
structure, aS seen in sections, reproduce 
that existing in life? 
3. What is the relation of the astral sys- 
tems to it? 
4. What is the finer structure and origin 
of the meshwork ? 
5. Can this structure be taken as typ- 
ical of all protoplasm; and if not, what is 
its relation to other forms of protoplasmic 
structure? 
After seeking for answers to these queries, 
we may finally inquire how they bear on 
the theoretical views briefly reviewed above. 
Sate ee EORROQ: 
be eteeSeS ey SAAR 
[N.S. Vout. X. No. 237. 
Incidentally, still another interesting ques- 
tion arises, namely: Is it possible to iden- 
tify any one of the three elements in 
question—granules, continuous substance, 
ground-substance—as the living substance 
or protoplasm proper, as distinguished from 
a lifeless metaplasm, and, if so, what are its 
structural relations ? 
Could we positively an- 
swer all these questions we 
should have taken a long 
step forwards in the study 
of the cell. Far from this, 
however, in point of fact, 
hardly any two observers 
have given exactly the same 
answers to them. Leaving 
aside the earlier views, we 
find in the recent literature 
of the subject two principal 
general views with a num- 
ber of modifications of each. 
The first of these agrees with the early 
view of Klein and Van Beneden, that the 
protoplasm forms a net-work, reticulum, or 
thread-work, composed of branching fibers 
embedded in a homogeneous ground-sub- 
stance’ which fills the interstices of the net- 
work, and with granules or microsomes 
lying along the course of the threads or at 
the nodes of the network. Many of those 
who adopt this interpretation further agree 
with their predecessors that the astral sys- 
tems formed during cell-division arise di- 
rectly through a rearrangement of the pre- 
existing network, about active centers of 
attractive or other forces, somewhat as iron- 
filings arrange themselves along the radia- 
ting lines of force in a magnetic field—an 
arrangement which bears a remarkably 
close though only superficial resemblance 
to the protoplasmic amphiaster. Boveri 
and some others, however, regard the astral 
system as having no direct relation to the 
preexisting network, believing that the rays 
either arise from a specific substance ( ‘ar- 
