2 j 2 NUCLEI AND NUCLEOLL 



wall, but gradually a membranous structure like the " cell 

 wall," may be formed and thus separate the bioplasm of the 

 new centre from that of the previously formed centre. 



Marvellous powers have been attributed to nuclei and 

 nucleoli, and by many these are still supposed to be the 

 active agents concerned in the process of multiplication and 

 reproduction. It is, however, certain that these phenomena 

 occur independently of nuclei and nucleoli. Nuclei are 

 always more intensely coloured by alkaline colouring 

 matters than other parts of the living matter, and nucleoli 

 are more intensely coloured than nuclei, a fact which is 

 alone sufficient to show the difference between a true 

 nucleus or nucleolus new centre and an oil globule, 

 which has often been wrongly termed a nucleolus. 



These new centres may he few or very numerous, and 

 there may be many successive series of such centres, and 

 each, when it comes to be developed, may manifest powers 

 different from the pre-existing series. And in certain cases 

 it would appear that as this process of formation of new 

 centres, one within the other, proceeds, new powers are acquired, 

 or, if we suppose that all possessed the same powers, 

 those masses only which were last produced retain them, 

 and manifest them when placed under favourable conditions. 

 Although nuclei and nucleoli are living matter, they do not 

 yet. undergo conversion into formed material, except as 

 regards the very thin envelope occasionally formed and 

 above alluded to. 



Under certain conditions the nucleus may increase, and 

 exhibit all the phenomena of ordinary bioplasm new 

 nuclei may be developed within it, new nucleoli within 

 them; so that ordinary bioplasm may become formed 



