REPRODUCTIVE ELEMENTS IN APUS AND BRANCHIPUS. 271 



fluid produced by the massing of the original diffuse staining 

 material within the nucleus into the small space of the chromo- 

 somes, by the process I have described — it will be seen that 

 this space, which in the first stage of the spindle figure repre- 

 sents the nuclearplasm, and retains the spherical character of 

 the original nuclear contour, has become very much enlarged 

 (figs. 11, 12, 23), not only in the direction of the spindle axis, 

 but laterally all round, so that it appears as a continually in- 

 creasing irregular area, occupying by far the greater part of 

 the celFs substance. Round this irregular space a rind of the 

 original kytoplasmic reticulum still remains (figs. 11, 12, 19, 

 23), and it will be noticed that at the junction of this rind and 

 the clear fluid within (fig. 19) a number of small staining points 

 exist, related to the angular spaces between the clear 

 globules and the non-miscible intervening fluid. 



These bodies grow continually, and their size marks the pro- 

 gress of the fusion of the clear central mass of fluid with the 

 similar constituents of the peripheral rind, just as the thicken- 

 ing of the chromatin bands was the measure of the fusion pro- 

 ceeding within the original nuclear limits. 



They continually stain more and more deeply with orange 

 and gentian violet, as the diffuse staining material dispersed 

 through what remains of the kytoplasmic network is swept 

 before the progress of the fusion into nodal points until, 

 simultaneously with its extension through the whole cell, they 

 are left as some twenty conspicuously dark bodies regularly 

 arranged on the periphery (figs. 13, 17). Close examination 

 reveals, however, that the fusion is not really complete, but 

 that fine achromatic threads connect these bodies one to 

 another (figs. 13 — 19) and to the inner group of chromosomes 

 in the manner described in an earlier part of my paper — a fact 

 which led me to devise the term dictyosome as expressive 

 of these peculiar relations. 



It will be seen that these dictyosomes appear at a definite 

 point in the karyokinetic metamorphosis, viz. the later phases 

 of the spindle figure ; and the cells which present these condi- 

 tions are comparatively large spherical bodies, which have 



VOL. 35, PART 2. NEW SEE. U 



