244 The American Naturalist. [March, 
with the other cells and with other filaments so that the blastoccele is 
traversed by a very complex network of anastomosing filaments arising 
from all the germ layers. These internal spinnings remain active up to 
the time of formation of the proctodæum, at least. 
The polar bodies spin, from the first, very fine pseudopodial filaments 
that soon unite with the egg and with the egg membrane as well as with 
filaments from the egg so that the polar bodies are henceforth (up to the - 
period of the late gastrula, at least) united to the egg, and to the result- 
ing cells, by threads of living material. 
The shape of the polar bodies may be changed as if distorted by con- 
traction of these filaments ; and change of place of the polar bodies seems 
also to be due, at times, to contraction of the filaments. 
In the anastomosing network that connects the egg with the polar 
bodies material is carried hither and thither in the currents that flow 
along the threads. 
Eventually the polar bodies may be taken in to the blastula, through 
the cleavage pore, and henceforth be connected with the network spun 
out from the inner ends of the blastula cells and, later, with the fila- 
ments from the entoderm cells of the gastrula also. 
The natural criticism that these spinning phenomena are abnormal, 
pathological, and hence of less wide interest, is met by the author with 
the statement that every precaution was taken to maintain normal con- 
ditions and that the eggs described were from lots that formed normal 
larvee, or even themselves grew into normal larve after the observations. 
Moreover it is granted that heat, polyspermy, immaturity of the egg 
and adverse states of the water resulted in very profuse spinning phe- 
nomena, but these truly pathological phenomena were very different in 
character and easily distinguished from the less obvious phenomena 
believed to be undoubtedly normal. 
It is thus claimed that in these normal Echinoderm eggs the proto- 
plasm can project delicate living filaments. That these are concerned 
in the formation of the egg membrane. That they connect the cells 
during cleavage and gastrulation so that the protoplasm is continuous 
trey grea the lass a n aparaton by the cell walls. 
e connecting filaments are contractile 
and that they aid in drawing the cells together, they may thus prove 
to be the basis of the so-called “ cyto-tropic ” movements exhibited by 
the blastomeres of various eggs. 
Moreover as these filaments are living hands and as material passes 
along them from one cell to another, the author thinks they may prove 
to be the means of that coordinating communication in the cell-aggre- 
