Modification of Germinal Constitution oj Organisms 235 



attribute is present in a higher proportion of indi\'iduals 

 than is normal. Such a race was created by means of 

 selection in which about 60 per cent of any generation would 

 have the modification and the other 40 per cent would 

 be without it. These proportions, however, have no sig- 

 nificance because those possessing it were just as liable not 

 to be able to transmit it, and those that did not possess it 

 were just as likely to have it show up in their progeny. 



The signaticollis stock had further been modified by a 

 selective process in that the amount of black pigment upon 

 the impressed punctations had been considerably increased 

 and by selection the impressed punctations had been 

 brought to a state where they existed in irregular parallel 

 rows. In the extreme of this selected stock which is not 

 constant, the appearance of the elytra is often that of two 

 closely placed irregularly parallel black lines. There is 

 an increase of pigment which finally continued from one 

 punctation to another, making a continuous line, in place 

 of a series of broken dots. 



These two stocks, modified b}* selection, were crossed 

 and gave in the first hybrid generation two types of adults: 

 a mid-t\q3e and one like the female iindecimlineata ty^e. 

 The mid-t}'pe, when inbred, gave four classes of full-grown 

 larvae, {whs), {it'JiS), (>'15), (yb), and from each of these 

 there developed three classes of adults, characteristic of 

 such hybrid operations. In the three classes of adults 

 developed from the {y\s) larvae in the second hybrid 

 generations are found a variable number possessed of a 

 combination of the selected characters of the parents; 

 that is, individuals which in normal crosses are of the 

 undccimlincata tj-pe, with the elytral stripes present as 

 one single solid band, in this cross ha\'e two narrow 



