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THE AMEBIC AN NATURALIST [Vol. XLII 



61 per cent, of the males having the right uppermost and 58 per 

 cent, of the females ; 59 per cent, of the parents and 60 per cent, 

 of the offspring put the right uppermost, so that there does not 

 appear to be any reproductive selection. The coefficient of asso- 

 ciation between parents of 0.02 demonstrates the lack of assorta- 

 tive mating. This last conclusion is in sharp contrast with the 

 results concerning other characters in man. 



There are a number of somewhat similar problems in the lower 

 animals which are of importance in the study of evolution. Thus, 

 the males of the common black cricket (Gryllus) usually keep 

 the right tegmen over the left. This results in one set of sound- 

 producing organs being functionless. In the closely related 

 Locustidae there is only one set of sound producing organs and 

 the tegminal position is fixed. It would be interesting to know 

 if mutations to the other position occur. The fish Anableps anab- 

 leps has the anal fin modified into an intromittent organ adapted 

 for side wise motion. On about three fifths of the males it can 

 move to the right and on about two fifths to the left. (Amer. 

 Nat., xxix, pp. 1012-1014.) A similar state of affairs exists in 

 the females, but with the relative frequencies reversed. Copula- 

 tion is effected by a right male at the left side of a left female 

 and vice versa. Whether the species will eventually split up into 

 two on the basis of this character or not would seem to depend 

 on how the anal-fin-twist is inherited. However, if the tendency 

 to twist to the right or to the left be inherited as a character apart 

 from sex there would seem to be no chance of two varieties or 

 species being formed, as each mating is between opposites. The 

 reversed position of the nerves in the optic chiasma of fishes was 

 found by Larrabee (Proc. Am. Acad. Arts and Sciences, xlii, 

 No. 12) not to be inherited. 



Frank E. Lutz. 



