THE ZOOLOGIST 



No. 834.— December. 1910. 



EECENT WOEK ON THE INHERITANCE OF 

 ACQUIRED CHARACTERS. 



By W. B. Alexander, B.A., King's College, Cambridge. 



It has long been known that a change in the environment 

 may produce a definite effect on the structure of many animals, 

 and until Weissman pointed out the theoretical objections to the 

 possibility of such effects being inherited, it had been thought 

 unnecessary to actually prove that this took place. 



Since this difficulty has been generally admitted, the onus of 

 proof rests with those who believe in the inheritance of acquired 

 characters, and it must be admitted that nothing sufficiently 

 satisfactory in the way of evidence has been adduced to shake 

 the disbelief in such inheritance. 



Certain recent work, nevertheless, suggests that, however 

 great may be the theoretical improbability of the inheritance of 

 acquired characters, the results of experiment cannot be inter- 

 preted on any other supposition. 



The work of Tower on Leptinotarsa, the Colorado potato- 

 beetle, has recently been brought prominently before the zoolo- 

 gical world by Professor Bourne in his Presidential Address to 

 Section D of the British Association at Sheffield. As this 

 Address appeared in ' The Zoologist ' (ante, p. 347), it will not be 

 necessary to describe Tower's results in detail. He found that 

 he could produce melanic varieties of the beetles by subjecting 

 them to a slight increase or decrease of temperature during the 

 Zool. 4th ser. vol. XIV., December, 1910. 2 m 



