MORPHOLOGICAL UNITY OF LIVING BEINGS. 163 



exhibited as formed of a tangle of fibrils, or better 

 still, of filaments or ribbons (in Greek, initoine\ which 

 are called chromatic filaments, because they are deeply 

 stained when the cell is plunged into aniline dye. In 

 each of these filaments, the substance of which is 

 called chromatin, the devices of microscopic examina- 

 tion enable us to discover a series of granulations like 

 beads on a string, the microsomes or bioblasts, con- 

 nected one with the other by a sort of cement, 

 Schwartz's linin, which is a kind of nuclein. 



And let us add, to complete this summary of the 

 constitution of cellular protoplasm, that it presents, at 

 any rate at a certain moment, a remarkable organ, 

 the centrosome, which plays an important part in 

 cellular division. Its pre-existence is not certain. 

 Some writers make it issue from the nucleus. At the 

 moment of cellular division it appears like a com- 

 pressed mass of granulations, which may be deeply 

 stained. Around it is seen a clear unstainable zone, 

 called the attraction-sphere ; and finally, beyond this 

 is a crown of striae, which diverge like the rays of a 

 halo — i.e., the aster. In conclusion, there are yet in 

 the cellular body three kinds of non-essential bodies: 

 the vacuoles, the leucites, and various inclusions. The 

 vacuoles diXQ. cavities, some inert, some contractile; the 

 leucites are organs for the manufacture of particular 

 substances; the inclusions are the manufactured pro- 

 ducts, or wastes. 



The Nucleus. — Every cell capable of living, 

 growing, and multiplying, possesses a nucleus of 

 constitution very analogous to the cellular mass 

 which surrounds it. The anatomical elements in 

 which no nucleus is found, such as the red globules 

 of blood in adult mammals, are bodies which are 



