818 The American Naturalist. [September, 
Tussock moth and several other less known species. They are pure 
white with a silky lustre and a reddish-brown tuft at the end of the 
abdomen from which arises the common name. The young larva pass 
the winter in a nest made by drawing together a few terminal leaves of 
a twig and lining and surrounding them with a mass of silken threads. 
It is not known exactly when or how it was introduced into America 
but it has been noticeably injurious for at least four years and it is pos- 
sible that it may have been imported with some foreign stock. It is at 
present confined to a small area in the vicinity of Boston. —W. F. F. 
EMBRYOLOGY.’ 
Spinning in Serpula Eggs.—In a paper’ published in the Jour- 
nal of Morphology, G. F. Andrews described remarkable and hitherto 
unrecorded phenomena in the eggs and larvee of star-fish and sea-urchins 
and designated them filose protoplastic or “spinning ” activities. 
These “ spinning” phenomena may be described as the formation of 
filaments extending out from the surface of the egg or cell and either 
straight, curved or bent; either separate or united to others; either 
simple or variously branched ; attached at the base, and either free at 
the tip or attached there also—to the egg membrane, to other filaments 
or to the surface of some other cell. What makes these threads recog- 
nizable as living protoplasm is chiefly the character of their activities. 
They are spun out from the living egg or cell as are the filose pseudo- 
podia of such creatures as Gromia, or as some of the pseudopodia of the 
leucocytes of certain Invertebrates. The processes are seen to grow 
longer or shorter, to branch, to join onto and fuse with others; they 
grow thicker or thinner, and often show nodular enlargements that 
pass along as in currents of living protoplasm. 
Such filose spinnings connect the egg with its membrane, the cleav- 
ing cells with one another, and the polar bodies with adjacent cells or 
with the unsegmented egg. They traverse the cleavage cavity and 
put cells of ectoderm, entoderm and mesoderm into communication 
with cells of the same and of other germ layers. 
Such intercellular connections are temporary, made and remade; 
they spin out as a cell is separating from its fellow in division and 
are not seen when the cells are closely pressed together. 
1 Edited by E. A. Andrews, Baltimore, Md., to whom abstracts, reviews and 
preliminary notes may be sent. 
2? See the AMERICAN NATURALIST. No. 363, March, 1897, page 242. 
