478 A NEW DOMINANT COLOR PATTERN AND COMBINATIONS 
the pattern S, anda new true breeding dominant pattern (Sm.) is the 
result. Isolation is not necessary for its perpetuation. 
New, true breeding, dominant color pattern complexes that might 
be considered units, were the elementary patterns composing them not 
individually known, may be, and have been developed in large num- 
bers by making individuals homozygous for two or more factors for do- 
minant patterns. This may be accomplished either by linkage when 
that is possible, or by bringing together the factors in different series, 
or on different pairs of chromosomes, when there is that arrangement. In 
either case isolation is necessary for complete perpetuation ; in separate 
cages, ifin the laboratory, and geographical isolation, ifin the wild state. 
Referring to the plate, the last four partly modified photographs, of 
the upper row, Paratettix texanus Hancock, illustrate progress in the de- 
velopment of complex patterns by the combination of factors each of - 
which appears to be on a different pair of chromosomes. The factor for 
the pattern B is supposed to be a mutant of a gene on one pair of chro- 
mosomes of the normal recessive +/+, © a mutant on another pair, 
and ® a mutant on still another (none of these mutations is known to 
have occurred in the laboratory). Bringing these together so that indi- 
viduals may become homozygous for any one, two, or three is a very 
simple matter and has been done many times. [+/+ (originally AA), 
BB and 6 6, Jour. of Genetics, Vol. 7, No. 1, ® pis new . Each is diffe- 
rent from the other and breeds absolutely true 1). 
Referring to the plate again, the lower row represents A Ppotettix eury- 
cephalus Hancock (Nabours ’19). The first four drawings represent 
probable mutants, though none has been detected as having originated 
in the laboratory. These four are capable of linking and it is a very sim- 
ple, though for T and K, an extended procedure to produce the com- 
plex patterns shown in the last three figures of this bottom row 2), 

1) J. B. S. Haldane, Journal of Genetics, Vol. 8, No. 4, after reviewing the 
author's data (Nabours ’14, ’17), suggests, possibly with good reason, that in- 
stead of being an independently segregating factor, © crosses over with Band the - 
other members of the multiple allelomorphic group to the extent of about 24 on 
in the males and 46 % in the females. Nevertheless, the end result with respect to 
the development of pattern complexes would be the same. 
*) The normal recessive type in A. eurycephalus, represented also by the sym- 
bol +/+, is so much like +/+ (old AA) in P. texanus that the one figure (Plate, 
+/+) will serve at present for both. There are so far eleven factors for color pat- 
