MUSEUM OF COMPARATIVE ZOOLOGY. T 
staining plasma; the inner ends of the cells, however, do not stain so 
deeply as the middle or peripheral portions. 
The cuticula (omitted from Fig. 3, see Fig. 5) is usually somewhat 
different in appearance from that at the extreme tip. In section we can 
distinguish two layers : an outer, thicker, deeply staining layer, which is 
not continuous but appears broken into larger or smaller bits; and an 
inner, thin, non-stainable and highly refractive portion, from which the 
first layer is often slightly separated. This second layer is closely applied 
to the underlying cells, which doubtless secrete it. Looked at from the 
surface (Fig. 10, æ.) the deeply stainable layer is seen to be broken into 
irregular polygonal pieces ranging from 2 a to 17 p in diameter and sepa- 
rated from one another by spaces ranging from 0 to 6 p. 
The mesoderm forms a loose epithelium, whose average width is less 
than that of the ectoderm (Fig. 3, ms’drm.). As a whole, moreover, it 
stains less deeply. In a portion of the gemmiparous zone, which lies 
about 180° from the budding region, the mesoderm has become so delicate 
a layer, if it exists at all, as not to be easily distinguishable. In the vicin- 
ity of the bud its cells have irregular outlines and extend out into the 
cœlom as though possessed of the power of amoeboid movement. The 
nuclei are spherical or ovoid, smaller than those of the ectoderm, and on 
the whole have smaller nucleoli. The cell body is highly vacuolated.. 
The vacuoles are not large and clear in outline, but whole regions of the 
cell body seem to be reduced to a non-stainable condition, and in some of 
these regions a fine network may still be observed. 
The proximal zone (Fig. 14, y to 8) is distinguished, soon after the 
first rudiment of the bud appears, by the diminished thickness of the 
ectoderm. The cells have become transformed from a columnar to a 
pavement epithelium. The nuclei are smaller, the nucleoli less prom- 
inent, and the cell body stains much less deeply. The cuticula is of 
two kinds, as before, but with this difference: the deeply staining outer 
part is less conspicuous, and the pieces are smaller and more widely sep- 
arated. Looked at from the surface, we find an appearance like Figure 
10, c., in which the dark bodies represent the deeply staining cuticula. 
These pieces are much smaller than those of the gemmiparous zone, 
ranging from 0.6 a to 9.5 a in diameter, and separated from each other 
by spaces ranging from 0 to 13 p. 
3. ORIGIN or THE POLYPIDE IN THE TERMINAL Bun. 
Observation having shown that budding in Paludicella follows definite 
laws, we ought to be able to discover the place and time at which buds 
