270 J. E. S. MOORE. 



increased in size somewhat, their relation to the spaces of the 

 intra-globular network being more pronounced, and we are 

 naturally led to the conclusion that such an increase is brought 

 about by the massing of the staining material in these angular 

 spaces, owing to the progressive fusion tending to lessen their 

 number and increase their size, just as it did with respect to 

 the chromatin within the old nuclear limits. 



Proportionately to the extension of this fusion, the tension 

 along the achromatic lines, on which the chromosomes are 

 suspended, becomes greater as the dark points (pseudosomes) 

 at their peripheral extremities retreat with the vanishing 

 achromatic network and its contained microsomes towards the 

 cell's circumference (figs. 10 — 12, 19). 



If we now try to realise what is actually taking place, it will 

 become apparent that the traction towards the periphery 

 through these points (pseudosomes) along the achromatic 

 threads, and ultimately upon the chromosomes themselves, 

 will tend to set itself along some axis across the nuclear figure 

 as a whole, and the points (pseudosomes) chosen will be those 

 on opposite sides which have, so to speak, the best foothold in 

 the periphery. The remaining points (pseudosomes) will tend 

 to glide as they do (figs. 9, 10, 12) towards the extremes of such 

 an axis, and a spindle figure will be finally set up (figs. 9, 12, 

 32, 23). From the figures just referred to, it will be apparent 

 that the coalescences of the points of attachment of the distal 

 extremities of the achromatic fibres (pseudosomes) become 

 marked out as centrosome-like bodies which travel away 

 towards the cell's circumference, and finally come to rest on its 

 extreme margin (figs. 11, 22, 23). In other words, these centro- 

 somes are virtually derived from a fusion of some of the pseudo- 

 somes, and these were in turn seen to originally correspond to 

 the angular spaces in a network exterior to the nucleus.^ 



In cells a trifle more advanced than those represented 

 in the preceding figures showing (fig. 19) the area of clear 



1 Professor Farmer has kindly shown me some preparations of Liliuin 

 which give exactly the same bundles of fibres related to separate granules, 

 any one of which might be individually considered as a centrosome. 



