194 JOHN E. S. MOORE. 



apices of the conical spiudle figure, round which the chroma- 

 tin elements lie. 



Fine protoplasmic fibrillse complete the space between these 

 elements and the apices, passing through a well-marked lighter " 

 zone in their immediate proximity (the "medullary corpuscle" 

 of van Beneden). 



The present condition of the cell is most favorable for the 

 study of this "medullary zone^' and central body. The zone 

 (fig. 3, c) presents a somewhat irregular contour, which appears 

 to correspond exactly in diameter to that region in which the 

 individual fibres of the astral radiation are compressed together 

 into a nearly homogeneous sphere, its size naturally being 

 directly related to their specific diameter (fig. 3, c). 



In the phases immediately succeeding this, the centring of 

 the spindle-fibres about the intermediate body becomes more 

 and more marked, until, for a more or less considerable pyra- 

 midal space on either side the division plane, they are com- 

 pletely fused (figs. 14, 15). This fusion presents the appear- 

 ance of a refractive dusky spot, which, growing at the expense 

 of the remaining spindle-fibres, spreads outwards as a hollow 

 sphere, whose optical section presents a pair of cornua (figs. 14, 

 15), and from this time onward it is undistinguishable from, 

 and presents the characteristics of, the archoplasm. 



This relation of the archoplasm to the spindle, and its final 

 regeneration from the spindle-fibres, is precisely what Platner 

 described as obtaining in the spermatocytes of Helix. 



While the archoplasm is thus regenerating itself on either 

 side of the division plane, the central bodies at the apices of 

 the whole spindle figure begin to approximate once more, 

 while the nuclei apparently recede until the bodies are lost 

 in their dark granulation. Hitherto I have been unable to 

 satisfy myself of their presence in this situation, for the axial 

 bay or perforation in which they ought to exist is filled by 

 astral radiations, which present the appearance of having 

 been sucked in after them (figs. 13 and 21). But it cannot 

 be doubted that they do pass this spot, as they reappear 

 immediately, creeping up the cones of fibres which remain 



