MICIIKJAN ACAr»EMY OF SCIENCK. 271 



Oeneticai Experiments me in progress to test the linkage relationsliip, it 

 possible, of the rogue fadors wilh (.(her factors which have been found (o 

 show Mendelian behavior. The phenomenon of true-breeding hybrids has been 

 interpreted by Muller (8) on the assumption of its being due to the action 

 of a pair of balanced lethal factors. It may be that the inheritance of the 

 rogue type is complicated by the presence of balanced gametic lethals. To 

 test the possibility a cytological study will be made of pollen formation in the 

 type plants which produce rogues, in the rogues, and in type plants of varieties 

 that do not produce rogues. Until the results from the two lines of inves- 

 tigation are known it would seem premature to suggest an explanation which 

 might account for the facts so far obtained. 



In conclusion, and as a statement of the problem, the facts which even 

 a tentative hypothesis would have to consider may be briefly restated. 



1. The change from type to rogue may manifest itself either from the 

 earliest stages of development of the plant or later during its ontogeny. The 

 first gives a plant called here a Rabbit-Ear rogue and the second change gives 

 an intergrading Rabbit-Ear rogue. (Confirmation of Bateson and Pellew, 

 1915). 



2. Between the type and Rabbit-Ear rogues are various sorts of inter- 

 mediates or intergrading plants that differ in the proportion of rogues found 

 among their offspring. (Bateson and Pellew, 1915.) 



3. The change trop^ type to rogue seems to be essentially a quantitative 

 one, affecting ten or more characters and involving such organs as the stem, 

 foliar parts, floral envelope, pods and seeds. In the latter there may be a 

 qualitative change, causing the green seed to be bitter in the rogue, while that 

 of the type is sweet to the taste. (Confirmation of Bateson and Pellew, 1915.) 



4. Rabbit-Ear rogues, from whatever source, breed true. (Confirmation 

 of Bateson and Pellew, 1915.) 



5. The change from type to rogue would seem a reversible one, so Ihiit 

 on rare occasions Rabbit-Ear rogue plants ma^ produce a branch that is fype- 

 likc in foliage characters. (Bateson and Pellew, 1915.) 



G. Rabbit-Ear rogue x type and the reciprocal hybrid are variable in the 

 seedling stage and may resemble either the type or rogue parent, or be inter- 

 mediate in form. At maturity, with I'are exceptions, the hybrids are like the 

 rogue parent. It must be emphasized that the change, even in the individual, 

 from type to rogue is a gradual change. It is true for both the intergrading 

 forms and the Fi hybrid. The fact is well demonstrated by the results of 

 measuring the stipules at the various nodes of the hybrids in which the change 

 takes place. (Figure 3.) (Confirmation of Bateson and' Pellew, 1915.) 



7. In the seedling stage the rogue plants are more variable in I'egard to 

 the ratio of length to breadth of the stipules than are the type plants. In 

 this regard the hybrid seedlings resemble the Rabbit-Ear parent, even exceed- 

 ing it in variability. (Table 5.) 



