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THE AMERICAN NATURALIST [Vol. XLI 



Carnegie Mus., 2 : 343-524, 1906) studied the crawli.hcs ..f Pennsyl- 

 vania and states that "anything that looks like a 'nmraiion" in de 

 Vries's sense is entirely unknown." Closely allied species eiilier have 

 distinct geographical distributions or if found in one locality they pre- 

 fer different habitats. 



W. D. Tower is of the opinion that "the evolution of the genus 

 Leptinotarsa and of animals in general has been continuous and 

 direct, developing new species in migrating races by direct ivs]X)nse 

 to the conditions of existence" {Carnecjie Inst., I'lil.l. 4S). \\v states 

 that "there is not at present evidence to show the origin of any heritable 

 variations in the soma"; and that "in these beetles we can get new 

 permanent variations by stimulating the germ cells and in no other 

 way." Such an inheritable character he produced artificially by sub- 

 jecting adult beetles to abnormal conditions of temperature, moisture, 

 and barometric pressure. The eggs produced and developing under 

 these conditions give rise to new forms which breed true even under 

 normal conditions. But the parent beetles when restored to normal 

 conditions produce offspring of the original type. The new forms are 

 therefore believed to be due to influences of environmental conditions 

 on the germ plasm. F. E. I.utz of the Cold Spring Harbor Station 

 has reviewed Dr. Tower's work from the mutationist's point of view, 



