Chromosomes and Genes 163 



the facts and interpretations taken from my former work (reviewed 

 1951) and just presented, which might be considered as putting out 

 feelers in the same direction, so far as they replace the concept of 

 mutation and (or) position effect as a chemical change by one 

 involving patterns and features of a field. Let me quote from a 

 general paper by a plant physiologist, who probably never had a 

 chance to hear of the facts and ideas just presented (Mothes, 1952). 

 After discussing the proteins as possible hereditary material, he 

 continues ( in translation ) : 



"One may safely say that the often mentioned, to all purposes 

 infinite number of chemical combinations of about 20 amino acids 

 possible in the formation of giant protein molecules receives its 

 importance only from this : namely, the chance that by diverse folding, 

 packing, spiralizing certain active groups may come to the outside of 

 the molecule and become active while others remain hidden inside, 

 as a kind of reserve which tomorrow in a new step of nature may 

 suddenly become exposed and thus endow the whole with new 

 properties. What we call a gene mutation does not necessarily con- 

 sist in a great change of chemical nature. It may just as well be a 

 change in pattern, which brings into action already present but thus 

 far hidden parts and thus produces new combinations and neighbor- 

 hoods of active groups and new electric fields." 



A second quotation of a similar character may be inserted here, 

 a statement by a cell physiologist and biochemist. In discussing the 

 problem of whether DNA may be considered as the genie material, 

 Mazia (1952) writes: "The 'physical basis of heredity' is something 

 in the chromosome which may or may not be DNA, but which follows 

 DNA for all the practical purposes of cytogenetics. We cannot be 

 sure that the question 'what is the genetic constituent of the chromo- 

 some?' is a meaningful one. The structure of the chromosome as a 

 whole is so astonishingly reproducible that the skillful cytologist can 

 always recognize a given one and, indeed, likes to give it a name 

 or number. It is well known that rearrangements even at the micro- 

 scopic level have hereditary consequences, and some have gone so 

 far as to contend that the genetic unit should be the whole chromo- 

 some. The regularities of chromosome structure may reflect regu- 

 larities of intermolecular relationships so decisive that it may prove 

 to be misleading in terms of molecules at all. We have seen in a 

 previous section how little is known of the intermolecular associa- 

 tions in the nucleus. The fractions that we isolate may be extremely 

 artificial entities, telling us a little about the weak points in the 



