TRANSFORMISM 259 



And it is interesting to note the importance, in this connection, 

 of *' lethal factors " in Mendelian studies. A lethal factor appears 

 to be some unfavourable combination of characters, or '' a double 

 dose " of some factor — in any case the organism that has a lethal 

 factor dies in the course of its development. 



87. ON HYPOTHESES OF TRANSFORMISM : 

 H. NEO-LAMARCKISM 



In such hypotheses is implied the notion that organisms change 

 their habits, functioning and structure by actual, inward efforts 

 or strivings and that they may have progeny that inherit the 

 changes brought about by these parental efforts and strivings. 

 Thus the changes in habits, functioning and structure acquired 

 or made personally by the parents produce changes in their 

 developmental organizations and so transformism occurs. 



87^. Acquirements. Among the variations from " the 

 ordinary " observed in a racial, wild population are those that 

 are called acquirements. Individuals displaying such are called 

 " variants by acquirement." Quite provisionally we define an 

 acquirement as some change of habits, functioning or character 

 that occurs in an individual organism after (so far as we know) 

 all the inherited characters have been fully developed. (But it 

 is, of course, never certain that any change that occurs after 

 development appears to have been completed is not simply an 

 example of exceptionally late development.) Acquirements may 

 be roughtly classified as (i) adaptations and (2) tmitilatiotis . 



Adaptatiofts . Typical examples of such changes of structure, 

 functioning and behaviour are : 



The whitening of the coats of some polar animals when the 

 winter conditions develop ; the thickening of the furs of cats 

 kept in cold-storage warehouses ; the thickened skin pads on 

 the hands of artisans who hold and use tools in particular 

 ways. 



Excessive secretion from the skin (in men) during hot weather ; 

 increased secretion from the kidneys at the onset of cold weather ; 



All animal training ; the opening of a latch by a dog ; recogni- 

 tion of the dinner bell by a dog ; expediency in traversing 

 labyrinths, etc., by crabs, rats, etc. ; 



Swimming by men and women ; making and using tools ; the 



