2 Inheritance and Evolntioti in OrfJiopteixi IT 



There is much confusion regarding the use of the terms dominant 

 and recessive, the interpretation and application of ratios, and the 

 definition, or determination, of characters. The terms dominant and 

 recessive remain part of the nomenclature, as if they were realities, 

 whereas they can have doubtful application only in crosses between 

 characters allelomorjjhic to each other in which one character is more 

 apparent (epistatic) and the other less apparent (hypostatic) ; or in case 

 of characters which are allelomorphic only to their absences, a character 

 being considered dominant and its absence recessive. Part of the con- 

 fusion in this matter has undoubtedly resulted, as will be shown later, 

 from the failure to recognize the distinction between the two classes of 

 characters. The 9:3:3:1 and 3 : 1 ratios are used freely and with 

 assurance, whereas there are in reality no such ratios. There appears 

 to be a lack, in usage at least, of appreciation of the distinctii)n between 

 characters which are allelomorphic to each other, nener fn an ahttence, 

 and those characters which are allelomorphic only to their absences, 

 nevei' to each other or any other cliaracters, and which e.xist only in 

 relation with, and in addition to, characters allelon\orphic to each othei-. 

 These matters are considered in the following paper which presents 

 further records of end results and some apjDlications of the breeding 

 work with the Grouse locust, Paratettix Bol. 



The colour patterns of the jjronota and femora of the jumping legs 

 are the characters considered. Observations have been continued on 

 the characters of long and short wingedness, but nothing further has 

 been ascertained than that these characters appear to be conditioned 

 by the environment, a tentative conclusion supported by evidence pre- 

 sented in my former paper. 



The suggestion that these forms be designated as species seems to 

 have been prematin-e and should be withdrawn : not that it is thought 

 they may never be considered as such, but r)rthopteran taxonomists are 

 as yet uncertain regarding the taxonomic position these forms should 

 occupy, and especially because this matter is not germane to the present 

 study. 



No names are assigned to the true breeding forms, or hybrids. The}^ 

 are designated by letters, the first eight being the same as before, with 

 six additional ones, two of them, LL and NN, not being figured. (The 

 G, BG and CG illustrated (Journ. Gen. Vol. III. PI. VI), but not other- 

 wise used, in the first instalment have subsequently been proven to have 

 been AA, AB and AC carrying homozygous doses of B, respectively.) 

 Each letter means that the pattern for which it stands is a unit which 



