No. 603] 



BUD-VABIATION 



135 



indicated by the raw data must be discounted by the 

 amount of deterioration shown by the unselected variety 

 under similar conditions. Such deterioration is very 

 common, and is due to disease, I believe, rather than to 

 any supposed disadvantage of asexual reproduction 

 per se. 



This category of facts has been cited under the discus- 

 sion of the inheritance of acquired characters, because 

 such phenomena have perplexed other than botanists. 

 Belief in the transmission of disease, or the effects of dis- 

 ease, by sexual reproduction was current for many years. 

 It is only since the possibility of infection in the egg 

 itself was demonstrated for various diseases, that the 

 true state of affairs has been known. 



Many other types of experiments designed to demon- 

 strate Lamarckism might be cited, but they have no direct 

 bearing on bud-variation except in so far as a positive 

 case would affect our general attitude on the frequency 

 of their occurrence. They are all similarly negative or 

 questionable, however, so that we must conclude with 

 Weismann that no case of inheritance of acquirements 

 has been proved beyond a reasonable doubt. In other 

 words we grant such a possibility but believe it to be so 

 rare or so gradual that practically it may be disregarded. 



In reality one could hardly have expected any other 

 conclusion from the type of experiment by which the 

 question has been attacked. Generalized they are some- 

 thing like this. Species X having been grown under en- 

 vironment A for numerous generations is removed to en- 

 vironment B. An adaptive change occurs which persists 

 during several generations. Later the descendants of 

 the original plants are returned to environment A and 

 the change is reversed. When the reverse cliange occurs 

 more slowly than the original change, it is argued that 

 Lamarckian inheritance is shown. The logic used to draw 

 such a conclusion is indefensible, even if the difficulty of 

 correcting proper! v for changes due to normal heredity 

 is left out of consideration. 



If acquired characters are inherited and the changes 



