002 Transactions of the Society. 



observation is made, in certain instances the exact course the dis- 

 placed nucleolus has taken can easily be seen by the path it has 

 apparently swept over the protoplasm of the cell. 



This feature having been observed by me on repeated occasions, 

 and its occurrence taking place almost without exception at a time 

 when the nucleus is in a resting condition, or only very slightly re- 

 moved from same, aroused my interest, and consequently I tried to 

 find a reason. 



The conclusion I came to after duly considering different pos- 

 sibilities was, that this can only occur for the reason that the 

 nucleolus at the time of the resting-stage of the nucleus must be in 

 a more compact and denser state than it is in later phases of mitosis : 

 hence offering at this time some greater resistance to the impact of 

 the microtome-knife, and is not cut clean through like the other 

 surrounding and apparently softer tissues. This failure to cut 

 through the nucleolus and instead push it out of position, is not, 

 or only rarely, seen in later phases of mitosis ; proving that at such 

 time when disappearance, or, as I should prefer to call it, imbibition 

 of the nucleolus is about to take place, the nucleolus is in a far 

 greater state of relaxity for this process; and again its varying 

 shapes and actions towards staining reagents goes towards proving 

 this latter condition. 



