DEPARTMENT OF BOTANICAL RESEARCH. 97 



Mutant "melanothorax" : body form, multitseniata; dorsal pattern, melanothorax; ventral 



pattern, multitaeniata; juvenile characters, decemlineata. 

 Mutant "obscura": body form, decemlineata; dorsal pattern, melanothorax, less certain 



elements; ventral pattern, decemlineata; body color, decemlineata; juvenile 



characters, decemlineata. 

 Mutant "white multitaeniata": body form, multitseniata; pattern, multitaeniata; juvenile 



characters, decemlineata; body color, ivory white, recessive. 

 Mutant "dark multitaeniata": body form, multitaeniata; pattern, multitaeniata; juvenile 



characters, multitaeniata; body color, dark, diffuse yellow dominant; new. 

 Mutant "dark multilineata" : body form, multilineata; pattern, decemhneata; juvenile 



characters, multitseniata; body color, dark, diffuse yellow-brown dominant. 



In these there are recovered in the mutants in recombinations the 

 following "characters" or groups of characters, which, however, are 

 acting in these mutants as units: 



Body form: multitaeniata, decemlineata, multilineata which was present in the original 



multitaeniata stock. 

 Pattern: decemlineata, multitaeniata, melanothorax, and obscura. 

 Body color: decemlineata, multitaeniata, ivory white, a new recessive condition, dark 



diffuse j'^ellow brown, a new dominant condition, an intensification of the condition 



in the typical multitaeniata parent. 

 Juvenile: decemlineata, multitaeniata. 



None of these "characters" is expressed in the form seen in the 

 mutants in the stem stock, which is a combination of all. In the 

 mutants, however, the characteristics come out with the purity indi- 

 cated. Each of these mutants breeds true in inbred lines without 

 limit, whether as pairs or population cultures. 



Thus far these recombination mutants involve the recombination of 

 what might be characterized as "huge blocks" from the original 

 parental organizations. From other work with these same species 

 it is known that the "blocks" shown in these recombinations which 

 behave as units are capable of being broken into many lesser units of 

 activity and behavior in crossing. 



A point of considerable interest, possibly of much significance, is 

 that it is always the "recombination mutants" that are the first to 

 appear after the initiation of the mutation process in the stem stock. 

 Later these mutants and (later still) the stem stock throw off the 

 second group of mutants, those due to breaking-up and rearrangement 

 of the characteristics that entered into the stem form. The second 

 group of mutants, in the main, behave as a multiple allelomorph, and are 

 extremely complex in composition and in behavior; consequently 

 their behavior and genetic composition have not been fully made out. 



A mutating stock of this kind, breeding freely in nature, producing 

 in every generation the recombination mutants and the alteration type 

 of mutant, would offer an almost endless series of possibiUties for the 

 production of a long series of types differing in aspect yet on the whole 

 having the same generic basis. Were this coupled with wide dispersal, 

 differing habitats, and the consequent possibiUties of ecological adjust- 

 ment and survival, it would seem to include all the necessary conditions 



