200 THOMAS H. BKYCE. 



relatively large number of sections obtained in this stage 

 indicates that it is of long duration. 



The varied figures drawn in figs. 18 and 21 are capable of 

 only one satisfactory explanation^ keeping in view that the 

 end result is always the same. The little rods come to be 

 placed radially on the spindle. Their central ends move 

 apart to form a T-shaped figure. The cross-piece of the T 

 representing the sej)arating limbs opening out on the 

 spindle, the stem of the T the outward directed, and still 

 united portions of the chromosomes. As separation proceeds 

 the stem of the T is pulled down until the figure is like two 

 commas placed end to end. It is obvious that this evolution 

 will open out the chromosome along the plane of the original 

 longitudinal split from within outwards, as is seen in a series 

 of drawings (fig. 21) of the chromosomes in profile view, but 

 when observed en face (same figure) it is equally clear that a 

 second longitudinal split has simultaneously been effected 

 along a new plane, fi'om without inwards, giviug the double 

 V-shaped figures represented in figs. 18, 19 and 21. 



If we describe the appearance in terms of the minute 

 terminal spheres of each rod, we see that the spheres come to 

 lie in a row exactly as Wheeler (1897) describes in Myzo- 

 stoma glabrum. The equatorial bodies then divide (figs. 

 16 — 18 and 21), but the terminal spheres of each rod remain 

 undivided, and are drawn away from the equatorial spheres, 

 so that the Avhole chromosome is lengthened out very greatl}'-, 

 and the apical spheres are carried far away from the equa- 

 torial, delicate, less deeply staining threads uniting thcni 

 together. The equatorial spheres, after remaining long in 

 contact in the equator, then part, and give rise to V-shaped 

 figures with a single apical and two equatorial spheres, one 

 at the end of each limb. These figures then shorten up by 

 the contraction of the elongated thread, and in the final 

 anaphase condense into short stumpy masses (figs. 19 and 21). 



These, when analysed, show that the apical sphere has also 

 divided, and we have produced small tetradal bodies exactly 

 like those in the prophases of the division, but of smaller 



