Feb. 15. I9IS Brachysm 397 



primary idea being that of transference of characters from one place to 

 another, which is not the same as abnormal or intermediate expression 

 of characters. Leavitt's idea of homoeosis may appear to be in better 

 accord with the Mendelian theory of heredity, which assumes that varia- 

 tions arise from differences in the transmission of characters, but meta- 

 phanic variations seem to represent differences in the expression of the 

 characters rather than differences in transmission. 



The present interpretation of metaphanic variations is based on the 

 recognition of a definite distinction between transmission and expression 

 as two essentially different processes, though usually described together 

 under the general term "heredity." Characters are often transmitted 

 without being expressed in visible form, as Darwin pointed out. Gallon 

 made a formal distinction between patent and latent characters — that 

 is, between characters that are brought into expression and those that 

 are transmitted without being expressed. Latency occurs frequently 

 in connection with Mendelian characters and has received much attention 

 in recent years, but the importance of the distinction between trans- 

 mission and expression is often overlooked and theories of transmission 

 are often applied to phenomena that belong to the field of expression. 

 With this distinction in mind, the idea suggested by metaphanic variations 

 like brachysm is not that the characters of one part have been trans- 

 mitted in some irregular manner to another part of the plant, but that 

 the normal sequence of changes or contrasts in the expression of the 

 characters is no longer observed. It is reasonable to believe that all 

 the characters are transmitted to all the parts, including those that usually 

 do not serve the purposes of propagation. Each of the intemodes of 

 the cotton plant is capable of reproducing all the other parts. From this 

 point of view the idea of translocation or transfer of characters no longer 

 seems adequate to account for abnormal intermediate characters like 

 brachysm. It seems more reasonable to think of metaphanic variations 

 as arising because the characters are being confused or combined in 

 expression. 



In connection with the theory of homoeosis Leavitt suggested that the 

 translocation of characters from one part of the body of a plant or animal 

 to another part opened the way to evolutionary changes, and many 

 examples were given in support of this interpretation. Intermediate 

 expression of the characters, involving a loss of specialization or differen- 

 tiation of parts, may also be considered as one of the ways in which plants 

 may vary and thus initiate evolutionary changes, but reasons have been 

 given already for looking upon metaphanic variations as negative or 

 degenerative changes of characters rather than as having progressive 

 evolutionary value. Instead of being taken as new characters that 

 are being added to the mechanism of transmission, metaphanic variations 

 may mean that the mechanism of expression has become deranged so 

 ^that the old characters are not normally developed. 



