18 



THE PHYSICAL BASIS OF LIFE 



one that is deliiiitely ordered, even tliougli it be not coni- 

 paral^le in precision with that wliich so impresses us in 

 ease of the imclear division. 



Vague indications of such a conclusion were long- since 

 given by the plastids of plant-cells, which are certainly in 



D E -^^iii^ p 



FIG. 8 

 Early stages of division iu the spermatocytes of the scorpion Centrums, showing 

 the aggregation of minute chondriosomes (mitochondria) to form larger rod- 

 like Ijodies near the nucleus (B, C), and their final aggregation to form a single 

 ring-shaped body {ch. in E, F). 



many cases, perhaps in all cases, self-perpetuating by 

 growth and division without loss of their identity, though 

 their distribution to the daughter-cells often seems to be 

 irregular. At a later period it was demonstrated that the 

 centrioles or central bodies, which form the foci of mitotic 

 cell-division, are likewise in many cases self -perpetuating 



