312 EDMUND B. WILSON. 



and the same should be true of the Long Island Banasa calva 

 if the two cases are really alike. But this question can only be 

 settled with additional material. All the individuals from west- 

 ern New York (Buffalo) and further west are of Type B. It 

 therefore seems not improbable that one of the types has been 

 lost in the western forms, or conversely, that Type A has been 

 added to B in Long Island, perhaps in a local colony or variety. 



COMMENT. 



The strong support lent by the foregoing facts to the general 

 theory of the individuality - - or, as I should prefer to say, the 

 genetic identity - - of the chromosomes is so obvious as hardly to 

 require comment. I will here only call attention to the interest 

 of the coupling of the ^--chromosome with one of the idiochromo- 

 somes in Metapodius. This phenomenon is doubtless comparable 

 in a general way to the coupling of the true odd or " accessory " 

 chromosome with one of the ordinary bivalents first briefly 

 recorded by Sinety * in the Phasmidae, and carefully studied in 

 several of the grasshoppers (in some of which the facts are more 

 complicated) by McClung 2 who has given an interesting discus- 

 sion of the subject. I have observed chromosome-couplings in 

 four families of the Hemiptera heteroptera and believe the phe- 

 nomenon will be found to be of wide occurrence in the insects, 

 and perhaps in other animals. It seems well within the bounds 

 of possibility that such chromosome-couplings may give the 

 physical basis of certain forms of correlation in heredity. If the 

 chromosomes embody the primary factors of heredity (the work- 

 ing hypothesis upon which I am proceeding in these studies), it 

 must no doubt be assumed that each chromosome contains the 

 determinants of many characters ; and the association of such 

 determinants in the same chromosome may imply the constant 

 correlation of the corresponding characters in heredity. But 

 in addition to this, certain correlations, such as are observed in 

 some forms of hybrids, might also be a result of a more or less 

 pronounced tendency of certain chromosomes to cohere in a 

 definite way, so as to be more frequently or even invariably 



1 La Cellule, XIX., 1901-1902. 

 2 BioL. BULL., IX., 5, October, 1905. 



