THE PHYSICAL BASIS OF LIFE 19 



by a similar process, and are thus handed on in a perfectly 

 definite manner from cell to cell during division. More re- 

 cent cytological studies prominently raise the question 

 whether still other formed bodies may not show a similar 

 behavior. This question has not yet been definitely an- 

 swered; l)ut evidence has been coming in which places 

 under suspicion the chondriosomes and the Golgi-bodies. 

 Both these are in many cases handed on during division 

 from mother-cell to daughter-cell, sometimes segregating 

 with a precision that almost suggests that seen in case of 

 the chromosomes. In manv cases the chondriosomes take 

 their place in separate groups about the equator of the 

 karyokinetic spindle, draw apart into corresponding 

 equal daughter-cells, move toward the poles, and enter 

 the respective daughter-cells (Fig. 7). Whether these 

 bodies individually considered have a permanent identity 

 and are self-perpetuating by division is still a disputed 

 question. LTndoubtedly they are sometimes actually cut 

 in tw^o during cell-division; and in one well-determined 

 case (spermatocytes of the scorpion Centrurus) all the 

 chondriosomes become aggregated into a single ring- 

 shaped body that is accurately divided in the course of 

 two ensuing divisions (Figs. 8, 9)." Often, it is true, the 

 chondriosomes seem to be passively sorted out or segre- 

 gated without division into two approximately equal 

 groups ; but in all these cases the possibility remains open 

 that they may multiply by division at an earlier period. 

 Were such the case their historv in division would be 

 comparable to that often seen in case of the plastids of 

 plant-cells; and in point of fact an important group of 

 observers, headed bv Meves and by Guilliermond,'" have 

 concluded from direct cytological observations that plas- 

 tids mav arise bv the transformation of chondriosomes 

 (Fig. 10). If this should prove to be correct, substantial 



