I()(> Inheritaiirc and involution in Ofthopt(i(( I 



(b) A leucoiiotus-lcucothurax iniilc tVom Exp. I, Fj (Table I, F3) 

 and a sister Icucothoiax (C) were mated and their F, (Ft) progeny were 

 as follows : 



LeiK^oiiotus- 



leucotliorax Leucothorax 



(BC) (C) 



Actual Numbers ... 69 66 ^i (t't) 



Expectation ... 67 -5 67-5 



These results are typically Mendulian, and close the report to be 

 made at this titne on the inheritance of colour patterns. 



IV. Long and shokt wingedness. 



(1) Long and sliurt wingedness in Nature. 



It is a matter of common observation that in many species of the 

 Acridiidae and Gryllidae there is dimorphism or polymorphism in the 

 length of the wings — some of the members bearing short and others 

 long wings. (In the Tetriginae, unless otherwise indicated, the word 

 wingedness refers to pronotum also.) The differences in some cases 

 have been considered by systematists sufficient to justify the giving 

 of different varietal names to the two forms (e.g. Tettigidea parvipennis, 

 Morse, and Tettigidea. parvipennis peninita, Morse, the short and long 

 winged forms of T. pennatus) (4). 



The studies of the difference in lengths of the wings in the Acridiidae 

 have been, so far as I can ascertain, confined to the field observations 

 and to the examination of collections in museums. However, in the 

 Gryllidae, Lutz (1907) has made observations concerning this pheno- 

 menon of long and short wingedness (pronotum not considered) in a 

 breeding experiment with Gryllus sp. His results brought him to the 

 conclusion that the length of the wings of the species with which he 

 worked was not conditioned by heredity, but by the environmental 

 conditions under which the individuals grew to maturity (6). 



In the Tetriginae, the differences in the length of the wings and 

 pronota are usually, though not invariably, dimorjjhie ; several varia- 

 tions from the long and short winged forms have been found, and some 

 individuals were strictly intermediate between the two extremes. It is 

 the usual occurrence to find a long pronotum with long wings and a 

 short pronotum with short wings, but a few \'ariations from this rule 

 have occurred as follows : in a few instances long wings have accom- 

 panied a short pronotum, and one individual exhibited a short pronotum 

 with one wing long and the other short (the various types are shown in 

 Fig. 2). 



