THE 



AMERICAN NATURALIST 



Vol. XLVI 



<;amktic coupling as a cause of 

 correlations 



G. N. COLLINS 



i When two distinct characters consistently occur to- 

 gether in the offspring of a hybrid, the phenomenon is 

 termed in Mendelian parlance "gametic coupling." If 

 the characters sometimes occur independently, but appear 

 together more frequently than they should by chance, the 

 term "partial gametic coupling" is applied. If the char- 

 acters occur together less frequently than is to be ex- 

 pected, the condition is termed "repulsion." while ii" they 

 never occur together in the same individual it is called 

 < < spurious allelomorphism. ' ' 



In mathematical language, characters that show par- 

 tial gametic coupling are said to be "positively corre- 

 lated," those that show repulsion, "negatively corre 

 lated." If they always occur together in the sain- i/oli 

 vidual, the correlation is said to be "perfect" or "com- 

 plete," while if they never occur together the negative 



of this nature, but with the attention focused on the idea 

 that all characters were independent units, the possibility 

 of such coherence was not considered, and it is sometimes 



