44 



PROTOPLASM. 



are to be seen, and it frequently happens that one or more 

 of these smaller spots or spherical masses may appear in 

 its substance, after a portion of germinal matter has been 

 detached from the parent mass. These are to be regarded 

 as new centres composed of living matter. Within these a 

 second series is sometimes produced. The first have been 

 called nuclei, and those within them nucleoli. Marvellous 

 powers have been attributed to nuclei and neucleoli, and 

 by many these are supposed to be the agents alone con- 

 cerned in the process of multiplication and reproduction. 

 Nuclei and nucleoli are always more intensely coloured with 

 alkaline colouring matters than other parts of the living or 

 germinal matter, a fact which is alone sufficient to show the 

 difference between a true nucleus or new centre, and an oil 

 globule, which has often been wrongly termed a nucleolus. 

 I have endeavoured to show that the bodies called nuclei 

 and nucleoli may be regarded as new centres which have 

 arisen in already existing germinal matter. These new 

 centres may be few or very numerous, and there may be 

 many successive series of such centres, each, when it comes 

 to be developed, manifesting 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 nu- 

 cleoli are germinal or living matter, they are not undergoing 

 conversion into formed material. Under certain conditions 

 the nucleus may increase, and exhibit all the phenomena of 



