116 SYMBIONTICISM AND THE ORIGIN OF SPECIES 



the terminology of the past on account of the more or less 

 specific conceptions associated with these terms. We are 

 immediately confronted by the phrase "acquired charac- 

 teristics." Although this term is sometimes used with a 

 different meaning from that originally proposed, to many 

 it conveys the idea of modifications that occur in an indi- 

 vidual as the result of outside influences of whatever 

 nature. In Sjrmbionticism, it would appear that the ac- 

 quisition of a microorganism and the morphologic re- 

 sponse of the host constituted an "acquired characteristic." 

 The theory of Symbionticism implies that such an acquired 

 character is "impressed" on heredity, and is transmitted 

 from generation to generation. It is apparent, however, 

 that we must differentiate between various kinds of "ac- 

 quired characteristics." We recognize acquired charac- 

 ters that are the result of extrinsic forces, such as tempera- 

 ture, Ught, moisture, chemical and physical agents, etc. 

 Other acquired characters are physiologic in nature and 

 may be produced by "use and disuse." We might also 

 include the "acquired characteristics" that are artificially 

 produced, such as dehorning of cattle, cutting of plumage, 

 castration, etc. We agree with the majority of students 

 of heredity, that a mechanism whereby acquired charac- 

 teristics of this kind might be transmitted in heredity has 

 never been demonstrated nor logically explained. The 

 "acquired characteristics" associated with Symbionticism 

 are of an entirely different nature and relationship to the 

 organism. 



It may be necessary to modify some of the ideas that are 

 held in connection with heredity, but these modifications, 

 perhaps, are not so momentous as they might at first appear. 

 It is also proper to point out that some of the conceptions 

 held in heredity are still in the hypothetical stage. Some 

 facts, apparently, have been established in regard to hered- 

 ity and development and something is known as to the 



