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R. T. Young 
arise similarly as I liave already suggestcd in Cysticercus pisiformis (1. c., 
p. 239), becoming later differentiated from each other as indicated by the 
results of differential staining in Moniezia. 
Taenia crassicollis. 
(Figs. 5 and 6.) 
In the anlagen of the sex dncts I find conditions similar to those 
already described. A densely packed mass of nuclei, which show some 
uncertain evidence of division, is here present. These are very iiTegiilar 
in size and shape and usually lack definite membranes and »nucleoli«. 
Tliey appear as irregulär niasses of nuclear matter scattered hetero- 
geneously thru the tissue. Numerous very small masses of darkly 
staining matter scattered among them are probably to be regarded 
as the anlagen of nuclei developing de novo. Some nuclei are 
granulär in structure and not very densely stained, while otliers are 
densely stained and nearly, if not quite homogeneous thruout. If division 
of pre-exi9tent nuclei were mainly accountable for the rapid nuclear 
increase in these regions, it is probable that more dividing nuclei would 
be found. 
In this worin I find many examples of the difference in staining 
reaction between different cells. In some of the sub-cuticular cells for 
example there is a more or less definite nuclear membrane and a pro- 
minent »nucleolus«, which maycontain a lighter area at the center, while 
adjoining cells show a mass of darkly staining granules. These differ- 
ences are found in material stained in all the different stains employed. 
In order to determine whether they represent phvsiological differences 
between different cells or are nierelv due to differences in density, or in 
the action of the stain, in different cells, I employed the following micro- 
chemical tests with fresh material. 
1. Staining teased preparations with methyl green. The stain here 
is diffuse and not selective. Both the densely granulär cells and those 
with tvpical 1 ) nuclei take the stain. In the nucleus both »nucleolus« 
and nuclear membrane are stained. 
2. Treatment with 50% potassium cyanide for 24 hours and staining 
teased material with carmine, haematoxylin and methylen blue. In such 
preparations the results are inconclusive. Tvpical nuclei are not evident 
while the atypical oncs appear to be discolored in part, having lost 
B Those nuclei possessing a definite »nucleolus« and membrane I sliall call typ- 
ical, those consisting of a densely stained mass of granules atypical. 
