Some Apparent Exceptions 99 



some, which, however, does not carry the factor 

 for perception of color, <□>- , the other without 

 the sex chromosome. The egg may be fertihzed 

 by either of these two, tj^jes of sperm, and the 

 results wiU be either, first, females that perceive 

 color, @; or, secondly, males that perceive 

 color, [•]. The color bhndness seems to skip 

 this generation. If now this woman mates 

 with a normal man, the eggs may be of two 

 sorts, those containing the sex chromosome 

 that carries the factor for the perception of 

 color, ® ; or those with the sex chromosome 

 that does not carry the factor for perception of 

 color, @ . The sperm from the normal father 

 win be of two sorts, those that carry the sex 

 chromosome containing the factor for per- 

 ception of color, and those that have no sex 

 chromosome. Either sort of egg may be ferti- 

 lized by either sort of sperm, so that we may 

 get in the next generation, first, normal 

 daughters, @; secondly, daughters like their 

 mother, ^ ; and color-blind males, \o] . In the 

 same way it is evident that if a woman like 

 the one just considered were to mate with the 



