70 HEREDITARY CHARACTERS 



hardly be considered as a new individual in the same sense 

 as a plant produced from seed. The practical result is that 

 we have a strawberry plant produced in which the compli- 

 cated process of fertilisation has been passed over, and that 

 in spite of this absence of the reproductive cycle, variations 

 may occur in the separated parts of the same individual in 

 plants. 1 Neither need we consider at present whether this 

 skipping of the reproductive cycle is due to the retention of 

 an ancient character, or a new character produced after the 

 evolution of bi-parental reproduction in any particular kind 

 of plant. 



The essential point at which we arrive is, that while 

 among all but the lowest multicellular animals variation 

 does not occur except upon the production of a new indi- 

 vidual, in plants variation may occur in parts of the same 

 individual, and that when a part of a plant is. separated 

 from an existing individual it may, under suitable con- 

 ditions, lead an entirely independent existence, and may 

 exhibit variation. This difference in potentiality as regards 

 variation between animals and plants depends upon the 

 fact that in plants a separated portion, in many cases any 

 portion, of an individual, is capable of reproducing all 

 the tissues, including the reproductive cells, that were 

 contained in the original individual. It has already been 

 suggested 2 that the germ-plasm in the higher animals is 

 probably separated at a very early stage in the develop- 

 ment of the individual, while in plants and in the lower 

 animals it is distributed throughout the organism. This 

 would account for this difference. Any comparison, there- 

 fore, between variations occurring in plants and variations 

 occurring in animals must be made with these facts in 

 view, and they must to some extent modify our ideas in this 

 relation. 



The comparison between variations occurring in wild and 

 in domesticated races of animals and plants should be made 



1 e.g. nectarines on peach-trees. See p. 68. 



2 See p. 57. 



