INTRODUCTION I 7 



remote ancestral form of the species. In this case, again, the 

 special peculiarity cannot depend on ' long-stalk pangenes,' 

 because the possession of a long stalk is not an intracellular 

 character. The specific form of the leaves and other parts of a 

 plant is likewise not due to the character of the individual cells 

 composing them : the serrated margin of a leaf, for instance, 

 cannot depend on the presence of ' serration-pangenes,' but is 

 due to the peculiar arrangement of the cells. The same argu- 

 ment would apply to almost all the obvious ' characters ' of the 

 species, genus, family, and so on. For instance, the size, 

 structure, veining, and shape of leaves, the characteristic and 

 often absolutely constant patches of colour on the petals of 

 flowers, such as orchids, may be referred to similar causes : these 

 qualities can only arise by the regular co-operation of many 

 cells. The characteristics of the human race may be taken as 

 another illustration. The peculiarities as regards the shape of 

 the skull, nose, &c., cannot depend on the mere presence in the 

 germ of pangenes, which are destined to form the hundreds and 

 thousands of different cells constituting the respective qualities ; 

 but they must be due to "a. fixed gr on piiig of pangeties, or some 

 other primary elements of the germ, which is transferable from 

 getieration to generation. 



The character of a species cannot depend only upon the num- 

 ber and relation of the pangenes in the germ. It is quite pos- 

 sible to conceive of two different species of totally different 

 structure in which the pangenes of the germ were alike in nature 

 and amount, the difference being solely due to the grouping of 

 the pangenes in the germ. De Vries, it is tnie, traces ' sys- 

 tematic difference to the possession of different kinds of pan- 

 genes,' and considers that ' the number of similar pangenes in 

 two species is the real measure of their affinity ; ' * but this 

 statement seems to me to be somewhat at variance with his 

 fundamental view, according to which ' a number of hereditary 

 qualities constitute the character of each individual species, thoiigJi 

 by far the greater majority of them recur in imuimerable other 

 species.'' Does he not, in so many words, emphasise the fact 

 that the almost formidable number of different pangenes which 

 are Required for ' the constiiiction of a single species ' does not 

 jj^ietessitate the existence of an inconceivably large multitude of 



< 



* Loc. cit., p. 73. 



