4gO MONTGOMERY. [Vol. XV. 



points than at others, there are no visible pores in it, so that 

 the nucleolar substance must be squeezed through the nuclear 

 membrane itself. When one takes a sponge filled with water 

 and presses it in the hand the water is forced out of it in the 

 form of jets or columns, which are radial to the surface of the 

 sponge ; exactly similar seems to be the method of the discharge 

 of the nucleoli in the case at issue, except that the nucleus is 

 itself actively contracting. Thus we find the greater number 

 of the nucleoli which lie in the cell body close to the surface 

 of the nucleus to be irregularly columnar or rod like in shape 

 (Fig. 198) and radially grouped around the nucleus. Those 

 which lie nearer the periphery of the cell, however, and which 

 had probably been discharged by a previous contraction of the 

 nucleus, are more irregular in form, and their axes have a less 

 regular position with regard to that of the nucleus. Further, 

 those ends of the rod-like nucleoli in the cell which are directed 

 towards the surface of the nucleus are usually more attenuated 

 than the opposite ends, i.e., a nucleolus lying in the cell close 

 to the nucleus has often the form of a pyramid the apex of 

 which is directed towards the surface of the nucleus, and this 

 form we would expect to result in the squeezing of a more or 

 less viscid substance, like that of the nucleoli, through the 

 nuclear membrane. I give only two figures showing the stage 

 of the discharge of the nucleoli from the nucleus, simply in 

 order to save time in the drawing of the numerous nucleoli ; 

 but my preparations show very clearly all the stages of this 

 process: one has only to examine sections of the mature leech to 

 find them in abundance. The extrusion of the nucleoli continues 

 until only about twenty, then a dozen, then four or five, and 

 finally only a single nucleolus (Fig. 199) remains in the nucleus ; 

 corresponding to these successive states of the discharge of the 

 nucleoli we find cells in which only a few nucleoli, and then 

 those in which the greater number of the nucleoli, lie in the 

 cell body. One nucleolus always remains in the nucleus, though 

 this one appears to differ in no wise from those which are dis- 

 charged. Those nucleoli which lie in the cell body (Figs. 197- 

 199) differ from those in the nucleus in their lesser density, 

 greater size, and different reactions to certain stains (we shall 



