Munson, Organization and Polarity of Protoplasm. 38 1 



The included granules of amorphous substances then obscure 

 the far smaller component particles of the centrosome. 



The Aster and Cytoplasm. In the spermatogonia 

 and spermatocytes of Papilio rutulus, the entire cytoplasm seems 

 to be converted into a huge aster during caryokinesis. The same 

 is also true of the cleavage cells of Ascaris, fig. 16, and also in 

 caryokinesis of leucocytes of Necturus, fig. 18. In this cell, the 

 size of the aster remains undiminished during the resting or re- 

 construction stage, fig. 17. In Ascaris, the aster seems to fade 

 away after division; and this is the case, also, in spermatocytes 

 of Papilio. May it not be true, that this disappearance of the 

 aster is more apparent than real? It is possible to trace the aster 

 during the long period of growth of the animal ovum, even when 

 this growth continues for several years, as in the case of Clemmys 

 fig. 6 — 11, pl. Ic, and also in the case of Limulus, figs. 19, 20, 22, 

 23, 24, pl. Ib. 



While the aster becomes less and less distinct, as the yolk 

 granules increase, there is no excuse for inferring that it is dis- 

 solved. Exceptionally successful preparations reveal a very 

 distinct aster in the various growth stages of the egg, figs. 20, 

 22, 23. These asters show distinctly the continuity of the astral 

 rays with the general network of the cytoplasm, fig. 20; and can 

 often be seen to occupy practically the entire cytoplasm. To 

 suggest that these are artifacts is manifestly absurd. Compare 

 the aster in the ovarian egg of Limulus, fig. 20 with the aster in 

 the fertilized egg of Ascaris, fig. 15. Compare also the aster in the 

 ovarian egg of Limulus, fig. 22, with the aster in the leucocytes 

 of Necturus, fig. 17. They are evidently similar bodies. 



The framework, so to speak, of the entire cytoplasm is an 

 aster with rays extending from a common center in the cyto- 

 plasm (often but not always the geometrical center of the sphere), 

 to the periphery; where, by the hardening of the interfibrillar 

 substance, the rays form the striation of the chorion as in the 

 egg of Limulus. 



When projecting beyond the limits of the cell proper, these 

 radial fibers form cilia, after secreting a thin outer covering which 

 hardens more or less. Several such fibers may combine to form 

 larger cilia. Where part of the reticulum enters in, a Pseudopodium 

 results, fig. 33, b, c, pl. Ia. 



In typical cases, the System of astral rays present the ap- 

 pearance of a geometrical spider's web, but the System is the 

 same in whatever plane the spherical egg is cut, provided the 

 section passes through the center. 



The concentric arrangement of larger granules, so clearly 

 visible in the aster of leucocytes, fig. 17, and also evident in the 

 segmenting eggs of Ascaris, is prominent, also, in ovarian eggs of 



