Activities of Polar Bodies. Ill 



diameters the polar bodies are plainly connected with each 

 other and with the surrounding cells of the blastula by delicate 

 threads of protoplasm that constantly change. There are 

 also characteristic tufts or brushes of more delicate threads 

 sent out from each polar body ; tJiese also constantly change. 



It will be noticed that the cells about the orifice also show 

 threads stretching from one to the other as well as to the polar 

 bodies. 



On the threads protoplasmic masses flow along to or from 

 the polar bodies or from cell to cell, and on the threads side 

 spinnings may take place, producing such branching, root- 

 like tufts, and anastomosing complexes as are partly repre- 

 sented in the figure. 



The peculiar contractile powers of the material of these 

 threads is illustrated in the figure in the case of a curved 

 connective that joins the angle of one process to the angle of 

 another. These processes extend from the two polar bodies 

 to two separate cells on the margin of the orifice or cleavage- 

 pore, and the curved connective seems as if tending to draw 

 the processes closer together by bending itself (compare loc. 

 cit. pp. 382-83) . 



Passing over many significant facts, we note that the polar 

 bodies may pass through the cleavage-pore into the interior 

 of the blastula and be connected with the complicated mass of 

 threads joining the mesenchyme-cells with the ectoderm and 

 entoderm in the gastrula-stage. 



Thus in these animals the polar bodies long continue to 

 act like Heliozoa, and acquire a living continuity with the 

 embryo which may extend to the gastrula stage in such a 

 way as to make them permanently part of the organism. 



In the large Nemertean, Cerehratulus lacteus, Verrill, I 

 find some spinning activities of the egg and its cells and most 

 marked activity of the polar bodies. Soon after their forma- 

 tion the polar bodies send out delicate Heliozoa-like rays, and 

 later characteristic star-like groups of processes that may 

 develop into long proboscis-like outgrowths armed with lateral 

 threads. From the first the polar bodies are continuous with 

 tlie egg and with one another by means of an exceedingly 

 delicate film of material that sometimes shows fine threads 

 and nodules within it, and seems living protoplasm rather 

 than passive excretion or " slime." 



In figure 2 the processes from the two polar bodies are 



indicated as seen under ocular 8, objective 2 millim., and 



draw-tube 160 millim., and drawn largely with the camera 



lucida. The egg was in the four-celled stage and about to 



divide again, so that there were more than eight cells fifteen- 



(J* 



