JuLy 14, 1899. ] 
the larger granules, or microsomes, are lemon 
yellow. This circumstance makes possible 
an observation of great importance, namely, 
that all the elements of the protoplasm are liquid 
or viscid. If the eggs of Ophiwra be crushed 
by pressure on the cover-glass the proto- 
plasm flows out, most of the alveolar spheres 
going in advance, while the granules and 
continuous substance lag behind. Mean- 
while, the alveolar spheres often run _ to- 
gether to form larger drops of all sizes, the 
origin of which is placed beyond question 
by their color. The same is true of the 
yellow microsomes, though this takes place 
less readily, and only under somewhat 
rough treatment. This demonstrates the 
liquid, or at least viscid, nature of both the 
spheres and the microsomes, and no less 
certainly that of the continuous substance 
in which both lie. As far as the alveolar 
spheres are concerned, the same observa- 
tion may readily be made in the colorless 
protoplasm of Asterias (Fig. 1, ¢), Echina- 
rachnius, or Arbacia, but I could never 
satisfy myself of the liquid nature of the 
microsomes in these forms. The case of 
Ophiura renders it highly probable, how- 
ever, that the granules are liquid in these 
forms also—a conclusion which I confess 
was a surprising result to me; for we are 
so accustomed from our studies on sections 
to regard the granules as solid bodies that 
we are apt to forget that sections show us 
only coagulated material. 
To sum up, a critical study of the living 
protoplasm of echinoderm-eggs shows that 
it is a liquid, or rather a mixture of liquids, 
in the form of a fine emulsion consisting of 
a continuous substance in which are sus- 
pended drops of two general orders of mag- 
nitude and of different chemical nature, as 
indicated by their staining reactions. The 
larger drops, forming the alveolar spheres, 
stain only slightly in hematoxylin, and 
constitute the so-called ‘ ground-substance ’ 
in the spaces of the meshwork ; these have 
SCIENCE. 3 
an average size, ranging in the various 
forms studied from 1.0 micron or less (Ar- 
bacia) up to 4.0 microns (Ophiura). The 
smaller drops, forming the granules or mi- 
crosomes, are very much more minute, and 
stain intensely with iron-hematoxylin. 
The presence of the larger drops determines 
the primary alveolar structure as described 
by Butschli. The smaller drops (‘granules’) 
lying between these give rise to the ‘ second- 
ary,’ or finer alveolar, structure as de- 
scribed by Reinke, and subsequently by Mrs. 
Andrews, as I understand these authors. 
Relations of the Astral Rays to the Meshwork. 
—We may now make a brief digression to 
consider the third question propounded 
above, namely: What is the relation of 
the astral rays and spindle-fibers to the 
alveolar substance? It is easy to see, both 
in sections and in living material, that in a 
well-developed aster the alveoli are ar- 
ranged in radiating lines between the astral 
rays (Fig. 4), precisely as Butschli and so 
many others have described. The rays 
themselves are, however, something more 
than the radially arranged inter-alveolar 
septa, for, in the first place, they are often 
much thicker than these septa, and, in the 
second place, they stain more intensely than 
the continuous substance. A careful study 
of the rays in the echinoderms, and in many 
other forms (especially in Nereis, Thalassema, 
Lamellidoris and Ascaris), leaves, I think, 
no room for doubt that, in sections at least, 
the rays are actual branching fibrillz, as 
described by so many observers since the 
time of Van Beneden, that thread their 
way through the continuous substance be- 
tween the alveoli, often in a zigzag course. 
The strongest evidence that they are fibrille 
is given by the appearance of the cut ends 
of the rays as they appear in somewhat 
excentric or rather thick sections of the 
asters. In such sections, particularly in 
the case of large and coarse asters like 
those of Nereis (Fig. 3, 6), the rays may be 
