The Somatic Nuclei of Certain Cestodes. 
151 
olus«, several subsidiary »nucleoH« and a heavy nuclear membrane. 
These masses, which I eonsider unquestionably cytogenic in character, 
contain very rare indications of dividing nuclei. Moreover thev are 
offen isolated front one another, except for the general parenchyma Strands 
which bind together all parts of the tissues of the worin. Occasionally 
nuclei are found unsurrounded bv any definite cell body, wliile granules 
stained in the nuclear dye employed, and which are I believe »nucleoli«, 
the anlagcn of future nuclei, may be found scattered thru both sub- 
cuticula and parenchyma. The significance of tliese facts will be taken 
up ander General Considerations. 
Here again is found the same difference in staining reaction of ad- 
jacent cells, both in those of the sub-cuticula and the parenchyma, as 
has been described for the forms already studied. Some of the cells stain 
lightly and have typical nuclei with distinct membranes and »nucleoli«; 
others have evident nuclei but the cytoplasm is filled with darkly stained 
granules, similar to the isolated »nucleoli« mentioned above, which give 
the wliole cell a much darker appearance; while in others still no nuclear 
structure is apparent, the entire cell being a dense granulär mass. Some 
of the densely stained cells, however, contain definite nuclei, as may be 
seen by close inspection, while others not more densely stained, evidentlv 
do not contain differentiated nuclei. In two cells of equal staining den- 
sity thruout, one of which contains a nucleus, which is lacking in the 
other, an Interpretation of such a difference based on differences in den- 
sity or irregulär action of the stain is a highly improbable one. In com- 
parison with my results from micro-chemical tests on Taenia crassicollis 
I can only interpret these differences as being physiological in nature, 
the apparently non-nucleated densely staining cells, in reality containing 
diffuse nuclear matter thruout. 
In the anlagen of the genital ducts of these worms I find very differ- 
ent conditions from those encountered in most of the forms studied. 
Here, instead of densely staining irregulär masses of nuclear matter, with 
smaller nuclear granules scattered among the larger, there is a proto- 
plasmic syncitium, in wliose meshes are larger or smaller, denser or looser 
protoplasmic masses, in most of which are found »nucleoli«, which vary 
in size from those which are very minute to those measuring occasionally 
1 micron m diameter. Usually these »nucleoli« do not measure over 
V 2 or V 3 jnicron, however. Some of these masses are surrounded by 
more or less distinct membranes, while in others there is no membrane 
evident. Occasionally, moreover, thev lack any nuclear structure wliat- 
ever, while in most there is beside the »nucleolus« and membrane no 
