32n 



THE AMEBIC AX NATURALIST [Vol. XLVIII 



one allelomorph of each pair, and that the eight factors thus 

 present in a gamete form a linked group, tending to segregate as 

 a unit in gametogenesis. Thus Nabours 's form A would give 

 gametes of the form Abcdefhi. AB would give gametes of only 

 two forms, one corresponding to A and the other to B, viz., 

 Abcdefhi and aBcdefki. Two other forms are possible, formed 

 by the exchange of A with B, and of a with b, but these will not 

 occur if linkage is complete. In dealing with the hybrid AB in 

 practise the factors cdefhi would not be put into the formula?, 

 as they are alike in all gametes. 



These rules would apply similarly to all other species and 

 hybrids. Therefore in the case in which the BEI individual 

 occurred, we would represent the male parent, which Nabours 

 designated CE, by bCci-bcEi, and its gametes by bCei and bcEi. 

 The female parent, which Nabours designates BI, we would 

 represent by Bcei-bcel, and its gametes would be Bcei and 

 bcel if linkage were complete. If linkage were not complete there 

 would occasionally be formed gametes bcei and Bcel. One of 

 these latter (Bcel) was probably formed and fertilized by a 

 sperm of the type bcEi, thus giving rise to the BEI individual. 

 No gametes corresponding to bcei appear to have been fertilized, 

 though of course we do not yet know what the appearance would 

 be of an individual so formed. 



This matter would be easy to test, and it is to be hoped the 

 cross may be repeated. If then BEI forms should appear again 

 and in these when mated to other forms the factors B and I should 

 be found to stay together to the same extent as they before sepa- 

 rated, it would show that close linkage, rather than multiple alle- 

 lomorphism explains this particular instance. 



It may be, too, that both linkage and multiple allelomorphism 

 play a part in the production of these phenomena. In any case 

 it seems that the test is at hand, and not difficult to perform, 

 excepting in so far as there are practical difficulties connected 

 with the rearing of the grasshoppers in sufficient numbers to 

 cover the point. 



Bridges, C. B. 1913. Non-disjunction of the Sex Chromosomes of Droso- 



phila. Jour. Exp. Zool., Vol. 15. 

 de Meijere, J. C. H. 1910. Ueber Jaeol.s..ns Xii.-htunysvemi.-he beziiglirh 



des Polymorphismus von Papilio Memnon L. $, etc. Zts. ind. Abst.- 



Nabours, R K. 1914. Studies of Inheritance and Evolution in Orthoptem. 



Shall, G. IT. 1911. Reversible Sex Mutants in Lychnis dioica. Bot. Gas., 

 Vol. Lit 



Sturtevant, A. H. 1913. The Himalayan Rabbit Case with some Consid- 

 erations on Multiple Allelomorphs. Am. Nat., Vol. XLVII. 

 Columbia University JOHN S. DEXTER 



