NOMENCLATURE 131 



have a way of removing the vowels without disturbing the rest 

 of the arrangement, I shall isolate six solitary consonants, eight 

 pairs of consonants, three bunches of triple consonants, and one 

 cluster of five consonants in a row. Each of these units, I would 

 conclude, was originally flanked on both sides by vowels. Other 

 words would yield other combinations, with the unambiguity of 

 distinction increasing with the length of the consonant clusters. In 

 very long words composed of only two vowels and two or three 

 consonants, unique clusters can be expected only very rarely; but 

 the relative frequency of the various combinations of consonants 

 (runs of 1, 2, 3, etc.) will be a means of unique differentiation, 

 even though it will not yet make it possible to reconstruct the 

 entire text. 



This is what we have been doing with many deoxyribonucleic 

 acid preparations. 



3. REMARKS ON NOMENCLATURE 



a. Definition of the term "homotope" 



If one monomeric constituent can take the position of another in 

 a definable segment of a polymer, we propose to designate it as a 

 homotope (from the Greek for occupying the same place). If 

 in the A-chain of insulin positions 8 to 10 are occupied by 

 Ala.Ser.Val in the ox^"^, but by Ala.Gly.Val in the sheep^^, I 

 would say that serine and glycine are homotopic with respect to 

 this sequence. The importance of this term for a consideration 

 of nucleic acid structure will become clear presently. 



b. Definition of the term ''pleromer" 



If in the total composition of polymers that are characterized by 

 balances such as the well-known pairing principles in deoxy- 

 ribonucleic acid^'"^, and in a more limited way in ribonucleic 

 acids^^, one constituent can ostensibly replace another in respect 

 to these balances, we propose to designate it as a pleromer (from 

 the Greek for filling up the measure). Thus, if in the deoxy- 

 ribonucleic acid of wheat germ^^ the molar quantity of guanine 



References p. 159 



