TRANSFORMISM 245 



Mendelian variants. We have seen that the plants of Pisum 

 sativum that are grown in a garden may be tall or short, may bear 

 green or yellow, or green and yellow peas, etc. We may, then, 

 see a pea-plant that bears yellow peas that are round and which 

 is tall : this is a Mendelian variant and the variable characters 

 are relative tallness, relative shortness, greenness of peas, round- 

 ness of peas, etc. It is to be noted that we cannot represent one 

 of such characters, say greenness, as a frequency distribution, that 

 is, there is only (in the classical Mendelian theory) one shade of 

 green, and not many shades, each with its own frequency of 

 occurrence. But in the later elaborations of Mendelism, instead 

 of one kind of character having a nearly constant value (say 

 intensity of colour, or shade of colour), and due to one factor, 

 there may be many intensities, or shades, which are due to the 

 operation of '' multiple factors." In such cases the variants may 

 be arranged in frequency distributions such as we have mentioned 

 above. 



Apart from such reservations the variations that we call Men- 

 delian ones appear in the individuals that we select for study, and 

 in some or all of the progeny of these individuals, or in some or 

 all of the progeny of the progeny and so on. They assort and 

 re-assort themselves in the hybridizing and other breeding experi- 

 ments that we make : that is, they are hereditary characters 

 appearing in a racial career in the Mendelian manner. The 

 individuals displaying them are '' Mendelian variants." Later 

 on we shall discuss categories of Mendelian variants and their 

 possible significance in racial transformism. 



Mutants. If we have much experience of the individuals of a 

 racial career we may observe novelties in that career. That is, 

 we may discover individual organisms that display some new 

 character — or, at least, some character which has not been seen 

 before, in all the individuals belonging to the race in question, 

 that have been studied. Such a novelty of structure is called a 

 '' mutation." Thus, after very many collections of the sand- 

 hopper, Gammarus, had been observed one individual was seen 

 that had red eyes : the ordinary Gammarus has brown eyes. It 

 is, of course, impossible to be sure that there had never, previously, 

 been Gammari with red eyes, but we may assume this, or at least 

 we may assume that if there had previously been red-eyed Gam- 

 mari that race had " died out." Now the red-eyed amphipods 



