No. 524] CHROMOSOMES AND HEBEDITT 475 



the chromosomes are concerned the results need not be 

 referred to any special kind of fusion of the combining 

 elements, but simply to the way in which the effects be- 

 come patent. Alternate inheritance and blended in- 

 heritance appear only to be extremes of the same process. 



This brings us to the inheritance of the spotted con- 

 dition, a class which has been a serious dilliculty on the 

 assumption of Mendelian dominance and segregation of 

 pure characters. The most striking case is that of 

 spotted animals or striped plants. Some regions of the 

 body are colored, other regions white, i. e. } they lack 

 pigment. On the assumption that the individual has the 

 capacity to produce pigment the presence of white spots 

 is inexplicable; on the assumption that the individual 

 lacks the power to produce pigment the colored spots 

 are inexplicable. A spotting factor is therefore assumed 

 whose presence accounts for spots. Its allelomorph is a 

 uniform coat whose presence does away with spots. A 

 more refined juggling would be difficult to imagine, espe- 

 cially when the presence of color is explained by the 

 presence of an enzyme and a color producer, and its 

 absence to the lack of one of these. Yet after appealing 

 to a purely physiological principle to explain color 

 versus no color, the explanation is thrown overboard in 

 the case of spotted animals and a mystical spotting fac- 

 tor is set up as an explanation. The humor of the situa- 

 tion grows when one thinks that the spotting factor may 

 produce a few white hairs on the tip of the tail, or a coat 

 nearly entirely white. To be logical there should be as 

 many spotting factors as there are hairs on the body. 



It has been shown that the spotted condition does not 

 follow by simply crossing a uniform color and an albino 

 — unless that albino has been derived from spotted an- 

 cestors. Hence spotting is not due to combinations of 

 this sort, but is due to a condition peculiar to certain 

 races. How can we interpret this peculiarity? The 

 great difficulty of explaining this class of cases must be 

 admitted, but I think that a possible interpretation may 

 be found in the following direction, although I am far 



