1896. ] NEW YORK ACADEMY OF SCIENCES. 173 
and achromatic structures, yet causes the deutoplasm spheres to 
lose their staining power more or less completely, while picro- 
acetic or pure sublimate brings them out sharply, causing them 
to stain intensely black with Hematoxylin. This seems to 
hold true in a measure for the centrosomes, since in many 
cases they fail to appear after treatment with sublimate-acetic. 
This agent also appears to swell up the centrospheres to a con- 
siderable extent, giving them in the fully-formed cleavage figure 
a diameter greater than the width of the spindle at the equatorial 
plate, while after picro-acetic their diameter is considerably less 
than that of the equatorial plate. In other respects, however, 
they present an appearance closely similar to that described by 
Wilson (11) in Toxropneustes after the same reagent. He then 
obtains a large reticulated centrosphere staining red by Bor- 
deaux or Congo red, surrounded by a dense crown of blue 
staining astral rays, and in which “there is absolutely nothing 
that can be identified as a centrosome.” ‘This renders it not im- 
possible,as Wilson has himself expressly pointed out,* that the 
centrosome may be here likewise present within the centro- 
sphere in the same form as in Thalassema. This is, perhaps, 
strengthened by the fact that both Boveri (2) and Reinke (9) 
have described in the Sea urchins a centrosphere more or less 
closely similar to that of Toxopneustes. On the other hand, it 
should be noted that in numerous preparations of the sublimate 
series the egg of Thalassema still retains traces of the behavior 
of the centrosome, so easily made out in the picro-ascetic series. 
Thus in the fully formed cleavage figure up to mid anaphase 
there is often seen a circular hyaline region, occupying the same 
relative position within the centrosphere as the cloudy area sur- 
rounding the centrosomes in the corresponding stages of the 
picro-acetic series. Within this area I observed in some cases 
two dark staining granules in every respect similar to the cen- 
trosomes, while in other preparations these could not be demon- 
strated. Moreover, in certain poorly preserved and much dis- 
torted picro-acetic preparations exactly such a clear area could 
be seen surrounding the centrosomes. In the sublimate-acetic 
series it was extremely rare to find a trace of the newly formed 
peripheral second cleavage amphiaster, though occasionally 
during and subsequent to the telophase the minute asters could 
be made out, with their centers, however, swollen up and bereft 
of centrosome. None of these appearances are described for 
Toxopneustes. It might be interesting to add that in Spherech- 
inus Hill obtains (5), after using sublimate-acetic, a distinct 
* Science, Vol. III., No. 54, Jan., 1896. 
