Elementary Species in Nature 61 



and hence has no fertilizing power. But the 

 young ovaries do not need such fertilization. 

 They are sufficient unto themselves. One may 

 cut off all the flowers of a head before the open- 

 ing of the anthers, and leave the ovaries 

 untouched, and the head will ripen its seeds 

 quite as well. The same thing occurs in the 

 hawkweeds. Here, therefore, we have no ferti- 

 lization and the extensive widening of the varia- 

 bility, which generally accompanies this pro- 

 cess is, of course, wanting. Only partial or 

 vegetative variability is present. Unfertilized 

 eggs when developing into embryos are equiva- 

 lent to buds, separated from the parent-plant 

 and planted for themselves. They repeat both 

 the specific and the individual characters of 

 the parent. In the case, of the hawkweed and 

 the dandelion there is at present no means of 

 distinguishing between these two contrasting 

 causes of variability. But like the garden- 

 varieties which are always propagated in the 

 vegetative way, their constancy and uniformity 

 are only apparent and afford no real indication 

 of hereditary qualities. 



In addition to these and other exceptional 

 cases, seed-cultures are henceforth to be con- 

 sidered as the sole means of recognizing the 

 really existing systematic units of nature. All 

 other groups, including systematic species and 



