NEW LIVING CENTRES. 47 



now becomes the nucleus, and new nucleoli make their 

 appearance in what was the original nucleolus. The whole 

 process consists of evolution from centres, and the produc- 

 tion of new centres within pre-existing centres. Zones of 

 colour, of different intensity, are often observed in a cell 

 coloured with carmine ; the outermost or oldest, or that part 

 which is losing its vital powers, and becoming converted 

 into formed material, being very slightly coloured, the 

 most central part, or the nucleus, although furthest from the 

 colouring solution, exhibiting the greatest intensity of colour. 

 These points are illustrated in PI. VI, fig. 19, and some 

 other figures. 



Germinal matter, in a comparatively quiescent state is 

 not unfrequently entirely destitute of nuclei, but these 

 bodies sometimes make their appearance if the mass be 

 more freely supplied with nutrient matter. This fact may 

 be noticed in the case of the connective tissue corpuscles, 

 and the masses of germinal matter connected with the walls 

 of vessels, nerves, muscular tissue, epithelium, &c., which 

 often exhibit no nuclei (or according to some, nucleoli), but 

 soon after these tissues become supplied with an increased 

 quantity of pabulum, several small nuclei make their appear- 

 ance in all parts of the germinal matter. (PI. VIII, fig. 36.) 



So far from nuclei being formed first and the other 

 elements of the cell deposited around them, they make their 

 appearance in the substance of a pre-existing mass of 

 germinal matter, as has been already stated. The true 

 nucleus and nucleolus are not composed of special con- 

 stituents differing from the germinal matter, nor do they 

 perform any special operations. Small oil-globules, which 



