16 Nature of the Genetic Material 



orderly reorganization in tlie proper pattern and differentiation under 

 the influence of the specific cytoplasmic environment. This demon- 

 strates that the compUcated pattern of the kinetosomes and their 

 products (e.g., the oral, stomatal spirals) does not divide simply, but 

 is built up anew from individual self-duplicating bodies under the 

 influence of field forces, gradients, and specific differences of the 

 environment.* 



Another interesting fact brings us back from the analogy to the 

 actual chromosomes. Lima-de-Faria (1952) described a remarkable 

 structural rule in the chromosomes of rye. The chromomeres in 

 pachytene show a strange size gradient in all chromosomes (see fig. 

 1). On both sides of the centromere a particularly large chromomere 

 is located. From here on the size of the chromomere decreases with 

 complete regularity toward the ends of the chromosome in a typical 

 gradient. Near the end is a knob formation with very large chromo- 

 meres; if there are any beyond, they are the smallest. It seems that 

 knob formation and length of the chromosomal arm control the rate 

 of this size gradient, which shows that the size of the chromomere is 

 controlled by its position within the chromosome. This is a further 

 proof that the dividing chromosome is not a gene string held together 

 for purposes of the mechanics of division, but is rather a functional 

 and structural unit in which the parts are in some respects controlled 

 by the configuration of the whole. 



This conclusion is based upon the assumption that it is possible to 

 compare the division of the chromosome, not to the separation of a 

 string of independent genie units after individual self-dupHcation, but 

 rather to the division of a differentiated organism. If we try to derive 

 a general picture of chromosomal division from the foregoing dis- 

 cussions the following hypothetical picture emerges: 



1. The centromere is self-duplicating in a general sense. This 

 means that its substance must be divided as the first step of chromo- 

 some division. It does not necessarily mean that the division consists 

 in a re-creation of a twin molecule according to the template model. 

 Since the only potencies of the centromere are division and outgrowth 

 of a fiber, the exact molecular duplication necessary for genie material 

 is not needed. A micellar bundle of self-duplicating units may be split 

 approximately under the influence of two arising fields, leaving aside 

 the moot question of how the body grows between two divisions. 



** In principle this was anticipated a long time ago by Schuberg as opposed 

 to R. Hertwig. Both were partially wrong, but Schuberg came nearer to the 

 truth. 



