EVOLUTIONARY THEORIES SINCE DARWIN 245 



of the teeth in grinding produced a stronger and 

 better molar tooth, and that the offspring shared in 

 this advantage. Since Weissmann's time, however, 

 every Lamarckian feels it necessary to suggest some 

 method by which the altered body of the parent can 

 produce modifications in the germ plasms from which 

 the young are to spring. One of our later biologists 

 begins to talk of some effect comparable with wire- 

 less telegraphy or induced electricity. He believes 

 that organs in the adult, not necessarily by direct 

 action, but by action from a distance, may alter the 

 germ. Of this, there is no proof at present. Others 

 have suggested that just as the ductless glands pour 

 into the blood chemical substances which materially 

 affect the growth and development of other portions 

 of the body, so similar enzymes, or other chemical 

 substances, may be sent into the blood, which sub- 

 sequently bathes the germ cells of the coming gen- 

 eration and produces the change. But of this, again, 

 there is no proof. We may believe that acquired 

 characters are transmitted, but we certainly do not 

 have a very clear idea as to how it can be done. 



One of the strongest objections to Darwin's idea 

 of evolution by natural selection of small and favor- 

 able variations, is that the process is too inconceiva- 

 bly slow to account for the enormous progress which 

 has been made. The answer has always been that our 



