CHAPTER IX 



IN the foregoing pages we have seen examples of animals 

 which are abnormal in possessing one or more distinct 

 characters, each affecting a particular part or system of 

 the body. Hence from a certain point of view these 

 characters are varietal and not specific. According to 

 De Vries mutants differ from one another and from the 

 parent species in every part of their constitution in all 

 their systems, although to a slight extent. The specific 

 character of a mutant or true species is a single indivisible 

 attribute, affecting the whole constitution of an organism, 

 having no parts such as might appear separately in different 

 individuals. In the words of De Vries, the specific quality 

 " must be regarded as the expresssion of a single character, 

 of a single unit, which arose as such and as such can be 

 lost." 



Varietal characters, on the other hand, affect only a 

 single system or part of the organism. The specific 

 character remains as a whole and is still recognizable as 

 such after a varietal character is added or subtracted. 

 This conception of specific and varietal characters as 

 things of a different order was a result of observations 

 made upon flowering plants. It is difficult to form an 

 opinion as to whether this distinction is recognizable 

 among vertebrate animals. It is not easy to see. Were 

 it obvious, there would be less difficulty in classification. 



