PART FIFTEEN 



CYTOLOGY 



Some years ago, the late Dr. Milliken is reported to have 

 said that all of the major facts of physics had been discovered 

 and that all that remained was the refinement of measure- 

 ments. Shortly thereafter the dissection of the atom began 

 and we suddenly had a "new" physics. Cytology was, at one 

 time, in a sort of doldrum period until refined chemical and 

 miscroscopic methods enabled men to make a real break- 

 through. Strasburgers paper represents the old frame of refer- 

 ence whereas the other papers have a more modern "flavor." 

 The revolution came, in brief, with the discovery that chro- 

 mosomes contained super molecules of deoxyribose nucleic 

 acid arranged in a double helix. It was further discovered 

 that the amount of this substance, DNA, in gametes was 

 half the amount contained in the regular cells. These facts 

 led to the prediction that the DNA was, in fact, the material 

 known as the gene. Genes of DNA have been transferred 

 from some forms to others leading to all sorts of interesting 

 predictions about making new species at will. 



The above development was cy to-chemical. Cytotaxon- 

 omy, as Dr. Anderson points out, attempts to deduce the 

 relationships of organisms by studying the numbers and 

 kinds of chromosomes in parents and their probable hybrids. 

 This, too, is a highly exciting and rewarding type of en- 

 deavor. 



For more papers in this area, read The Cell by Carl P. 



Swanson. 



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