12 Mutual Independence of Hereditary Characters 



is by no means inseparably connected with the other fac- 

 tors of plant nature. 



Other factors are the predispositions (Anlagen) 

 which enable many species to produce definite chemical 

 compounds. First of all, the red and blue coloring mat- 

 ter of flowers, then the different tannic acids, the alka- 

 loids, etherial oils, and numerous other products. Only 

 a few of these are limited to a single species, many recur 

 in two or more species, which are often systematically far 

 apart. There is no reason for supposing that, in every 

 individual case there is a different mode of origin for 

 the same compound; rather it is obvious that essentially 

 the same chemical mechanism underlies the same process, 

 wherever we find it. 



In a similar manner we must also accept as possible 

 the analysis of the morphological characteristics of the 

 species. It is true that morphology is not by any means 

 so far advanced that such an analysis could be carried out 

 in every individual case. But the same leaf-form, the 

 same leaf-edge, coarsely or delicately notched, recur in 

 numerous species, and even the customary terminology 

 teaches us that the configurations of all the various leaf- 

 forms are composed of a comparatively small number of 

 simple characters. 



It would be superfluous to accumulate instances which 

 are easily accessible to every one, and it is only a question 

 of thoroughly familiarizing one's self with these ideas, so 

 that the synthesis of the whole out of its component parts 

 is clearly recognized. It will then be seen that the character 

 of each individual species is composed of numerous hered- 

 itary qualities, of which by far the most recur in almost 

 innumerable other species. And even if, in the building 

 up of any single species, such a large number of these 



