Structure and Division of the Vegetable Cell. 207 



represent the denser material of the nucleolus, since it forms 

 a bridge-like connection between (Plate X. figs. 3a and 3&). 

 It will be noticed that in fig. 3& two nucleolo-nuclei are 

 visible on opposite sides of the dense portion ; further, 

 the nucleolar membrane has, as far as can he seen^ dis- 

 appeared, but, as stated below, this again makes itself 

 visible ; I therefore think it probable that these swollen 

 sac-like expansions are inflations of the nucleolar mem- 

 brane, and that during this period division of the nucleolo- 

 nucleus is carried out, since, in all subsequent changes, 

 two nucleolo-nuclei are present. The nucleolus again 

 assumes its normal shape, its membrane reappearing, and 

 as well defined as in a resting state. After this it in- 

 creases markedly in size, as if an abundant nutrient supply 

 w^ere being handed on to it ; and this may furnish an 

 explanation of, and reason for, the aggregation of the 

 protoplasm, since there would then be provided a source of 

 nutritive material immediately round the centre of increase 

 and action. 



The next step in the process of division is a very strik- 

 ing one, and enables us somewhat to realise how little is 

 our knowledge of the vital energies which reside in living 

 matter, while it teaches us that in bodies apparently 

 structureless profound molecular changes may be going 

 on. The nucleoplasm is forced through the nuclear mem- 

 brane, and aggregates itself on the two opposite sides, where 

 the protoplasm had already accumulated, giving the idea, 

 now no longer, of two pale masses of almost homogeneous 

 protoplasm, but of dark and closely packed amoeboid-look- 

 ing lumps ; and to these (not to the nuclear membrane) the 

 radiating threads are attached. These sides we may now 

 term the poles of the nucleus. The nucleoplasm of the 

 poles is still connected with the nucleolus by fibres, which 

 pass through the nuclear membrane (Plate X. fig. 4). The 

 question may now suggest itself, Why do we believe that 

 the nucleoplasm is forced, rather than pulled out ? To this 

 we reply that the only visible agents by which this could 

 be effected, are the radiating threads ; but at this time, 

 instead of being tense, they are loose and flaccid. The 

 whole after behaviour of the nucleolus, moreover, confirms 

 the supposition, that it now is the centre of two opposing 



