No. I.] FILOSE ACTIVITY IN METAZOAN EGGS. 3 



first cleavage, as elsewhere mentioned.^ Later, in the gastrula 

 stage, filaments were seen passing from the ectoderm to the 

 membrane. However, no undoubted case of filaments connect- 

 ing cells was observed in the comparatively few eggs studied. 



The eggs of a nudibranch mollusk, Tergipes despcctus (?), 

 were examined alive at a later date, and showed similar filose 

 phenomena. In an egg not yet divided and having one 

 polar body formed, numerous fine filose threads were seen pro- 

 jecting from the surface into the wide space between egg and 

 membrane. Most of these filaments were confined to one 

 quarter of the periphery, as seen in optical section; but one 

 isolated, blunt, branched process came up some distance from 

 the others near the polar bodies, which were of unequal lengths, 

 a few longer ones reaching out halfway to the membrane. The 

 longer ones often showed short branches at the tip and swellings 

 along their length, suggesting those on the pseudopodia of 

 filose Protozoa. Moreover, a vibrating particle beyond the 

 finest filaments, and scarce seen with ocs. 6 and 8 and obj. 2 

 mm., moved out and then back again toward the egg, as if it 

 might have been traveling upon some finer filament not seen. 



The early stages of several marine lamellibranchs were very 

 briefly examined. In Yoldia limatiila an egg before dividing 

 was seen to send out innumerable fine filaments from a thin 

 layer of waving ectosarc. As these filaments were crowded 

 together and radiated directly outward, they looked not unlike 

 the cilia the larva developed, but they were much finer. These 

 filaments did not spring from the entire surface of the egg, but 

 from large areas. At one point a comparatively coarse process, 

 suggesting an icicle in high refractive power and shape, pro- 

 jected amidst the finer filaments. As there was no membrane, 

 all these filose processes projected freely into the sea water. 



Again, in a much more prolonged study of the eggs of the 

 large nemertean worm Cerebratiihis lactetis Verrill, certain filose 

 phenomena were seen before and after the first cleavage. The 

 pear-shaped egg removed from the female had a more or less 

 pronounced prolongation at its pointed pole. From this pro- 



1 Andrews, E. A., " Spinning in Serpula Eggs," American iVaturalisi. Septem- 

 ber, 1897. 



