STRAIN AND INDIVIDUAL IDIOSYNCRASIES 



33 



are got representing a continuous series of gradations from white up 

 to well-marked salmon, the whitish and pale salmon shades being most 

 abundant. But not always ! As for example : 



Fi Italian Salmon X Chinese White; produced 60 zebra and 60 

 white larvae and cocoons ranging from very pale to strong salmon. 

 Fo Hyb. X hyb. ; produced very pale salmon cocoons. 

 F2 Hyb. X hyb.; produced 31 creamy to salmon cocoons. 

 F2 Hyb. X hyb.; produced 38 whitish to salmon cocoons. 

 F2 Hyb. X hyb.; produced 31 salmon cocoons. 

 F2 Hyb. X hyb. ; produced all salmon to strong yellowish 

 salmon cocoons. 



And repeated groups of F2 generations varied among themselves 

 although the parents of all the members of each group were brothers 

 and sisters (i. e., all from a single F^ lot). But in the large majority 

 of lots the break-down was complete and the cocoons ran continually 

 from white to salmon, with the modal shade a very pale salmon. 



Conclusions. — Not to prolong unduly this discussion an end may 

 be made of the presenting of data. The evidence could be piled high 

 by introducing the details of other series of rearings, but this seems to 

 me unnecessary. 



It seems plain to me that the inheritance of the cocoon color 

 character is not a consistent one. The characteristic may behave in 

 strictly alternative and nearly exact Mendelian manner. Or it may be 

 inconsistent as to dominance within the same races; that is of a pair 

 of allelomorphs one may be dominant in one cross mating and the 

 other dominant in a second cross mating between the same races. 

 While in a third cross mating between the same pure races neither 

 cocoon color may be dominant but half or another proportion of the 

 offspring may be of one color and the rest of the other color. Or the 

 color characters may not behave as a strictly alternative character but 

 may blend or break down in transmission. 



These variants or deviations from a strictly alternative Mendelian 

 character may appear within the same race crossings and even within 

 a single group of F2 and F3 generations, all derived from a common 

 parental or grand-parental crossing, or these deviations may be char- 

 acteristic of crossings between different races or strains possessing 

 similar cocoon color. In the first place the deviations or incon- 

 sistencies in inheritance behavior may be attributed to "individual 

 idiosyncrasies"; in the second to "strain idiosyncrasies." 



