SOiME OBSEKYATIONS ON A NEW GREGAKINK. 279 



which attention has been frequently called, is the intense 

 staining" capacity shown by tlie achromatic mass, both at its 

 first appearance and later in the fully formed spindles. This 

 applies equally to Delafield's htematoxylin and to Heidenhain's 

 method, which latter is known to stain plastin-substance 

 darkly. Now the chromosome material, when first detected, 

 is seen as streaks lying on the spindle-fibres near the poles ; 

 or, when the fibres are seen in optical section, as a line of 

 contiguous granules (fig-^. 12 and 13). No preparation 

 showing an equatorial arrangement of the chromosomes w;is 

 obtained, although, of course, this does not prove the non- 

 existence of such a stage. Fig. 12 shows some of the 

 chromatin streaks directly continuous with the well-marked 

 terminal mass ; and it is thus possible that this mass repre- 

 sents a collection of chromatin which has been delivered by 

 the spindle-fibres. I suggest, therefore, that throughout the 

 division the spindle-fibres are carrying chromatin in a form 

 unrecognisable as discrete particles, until it undergoes con- 

 densation towards the poles of the figure. With the 

 appearance of the vesicles the chromatin elements disappear 

 ivoxn the spindle, leaving only the few scattered granules of 

 figs. 12 and 15. These vesicles would thus appear to have 

 been formed from the chromosomes of the earlier stages, 

 and supposing them to be indeed daughter-nuclei, it is 

 conceivable that they go on growing at the expense of 

 chromatic substance still uncondensed in the spindle-fibres, 

 until finally they become free as the first pair of daughter- 

 nuclei. This theory would account for the staining properties 

 of the spindle ; and the absence, at the earliest stage of the 

 division, of definite chromosomes. 



As regards the origin of the chromatin of the daughter- 

 nuclei, there is nothing upon Avhicli to dogmatise. We have 

 the fragmentation of the original chromatin masses, which 

 proceeds until the resultant particles are indistinguishable, 

 and we have the breaking-up of the karyosome, both of 

 which might supply a source for the chromatin. That this 

 chromatin is being in some way drawn up on to the spindle 



