354 EXPERIMENTAL STUDY OF INHERITANCE 



variety, yields Giant Purple, which, when inbred, has as progeny 

 Giant White, Giant Purple, Mars, Her Majesty, and a new form. 



Mr. Bateson interprets this kind of phenomenon as due to 

 the analysis of a composite character into several sub-characters, 

 while others suppose that latent characters from previous pedigree 

 are liberated by a departure from the usual routine of inbreeding. 



Correns has investigated the interesting case of Mirabilis jalap a. 

 The white variety, alba, crossed with the yellow variety, gilva, 

 yields a hybrid with rose flowers and red streaks. When this 

 is inbred the progeny include forms with white, red, rose, yellow, 

 yellowish flowers, with or without various kinds of streaks. 



In his important work of 1909, Mendel's Principles of Heredity, 

 Professor Bateson wrote : "Of the various cases alleged as 

 exceptional, or declared to be incompatible with Mendelian 

 principles, few have any authenticity. . . . The progress of 

 research has gone steadily to show that facts of heredity which 

 at first seemed hopelessly complicated can be represented in 

 terms of a strict Mendelian system." On the other hand, we 

 find an experimenter like Professor W. L. Tower declaring 

 (1910) that " in the attempt to preserve the letter of the law 

 of Mendelian theory of unit characters with segregation in 

 gametogenesis, a host of hypotheses have been developed in 

 order to save the original theory." 



4. Illustrations of Mendelian Inheritance 



How far has Mendel's Experience been confirmed ? There 

 has ^en confirmatory work by Correns (on peas, maize, and 

 garden-stock), by Tschermak (on peas), by De Vries (on maize, 

 etc.), by Bateson and his collaborators (on a large variety of 

 organisms), by Darbishire (on mice), by Hurst (on rabbits), by 

 Toyama (on silk-moths), by Davenport (on poultry), and so on. 

 There are some difficulties and not a few discrepancies, but, as 

 Bateson says, " the truth of the law enunciated by Mendel is 



