Henry S holer Williams . 687 



Lower Devonian" and that " it is a later fauna than the 

 Tilestone or Downtonian of Great Britain or the terminal 

 marine fauna of Arisaig, Nova Scotia" (1916). 



In regard to evolution, Professor Williams always 

 fully accepted the fact. To him, species are as mutable 

 as are organisms. "The principle of mutability must be 

 recognized in the phenomena of development before we 

 can rightly comprehend the laws of organic life." 

 "Variability is the expression of the fundamental energy 

 of the organism, and is not an irregular accident. 

 Heredity is the expression of the acquired adjustment of 

 the organism to the conditions of its existence. Mutable 

 heredity sounds like a contradiction; so did mutable 

 species a century ago ; but it is only as heredity is muta- 

 ble that evolution is possible" (On the Genetic Energy 

 of Organisms, 1898). 



"We must seek for the immediate determined causes of 

 variation not in natural selection, nor in any of the envi- 

 ronmental conditions, either direct or indirect, by which 

 hereditary repetition is established, but in the phenomena 

 of individual growth and development, and in the more 

 fundamental processes of cell growth and metabolism" 

 (Variation versus Heredity, 1898). 



1 ' Whether the vital phenomena are latent in matter or 

 not is a matter of speculation. Whenever vital phenom- 

 ena appeared, they appeared in phenomena exhibited by 

 matter. Whenever inorganic matter becomes vitalized, 

 however that result may be accomplished, variation takes 

 place and distinguishes it from matter in every other 

 condition." "Variation, as a process of becoming dif- 

 ferent, is a characteristic of living bodies" (On the 

 Theory of Organic Variation, 1897). 



In retrospect we may say that Professor Williams 

 worked long and faithfully, attaining good results, and 

 that most of his work will be woven into the permanent 

 record of Historical Geology. We see him far more 

 effective and better understood in his writings than in 

 his public speaking and teaching. His publications are 

 the record of work well done, and to the succeeding gen- 

 erations of geologists they will be the living thoughts of 

 Henry Shaler Williams. 



Chaeles Schuchert. 



