Further Studies on the Apogamy aud Hybridization of the Hieracia. 28 1 



also Bateson (1909, p. 285) — means, that there is no settled difference 

 between segregating variety hybrids and non-segregating species hybrids, 

 and here I quite agree with these authors. 



JOHANNSEN reports briefly the main points of my investigations 

 on ^he Hieracia which I had placed at his disposal for this purpose, 

 and points out, that: "diese. Sache eine große Bedeutung haben kann 

 für das Entstehen neuer Biotypen" (p. 425), but that we are still 

 only at the beginning of the investigations. A little later he comes 

 back to the constant Hieracium hybrids and says: "Es sind eben 

 gleich als F^, neue Rassen oder Species gebildet. Denn diese 

 Biotypen verhalten sich ja wie homozygotische Organismen — ja sie 

 sind es wohl eigentlich" (p. 437), — sentences with which I fully 

 agree. Moreover, the investigations have now confirmed Johannsen's 

 supposition in the following sentence, viz.: "Inwieweit das Nicht- 

 spalten, wie es bei den S. 425 erwähnten Ostenfeld' sehen Hieracium- 

 Bastarden wohl der Fall ist, oft mit Apogamie zusammenhängt, 

 läßt sich noch nicht' entscheiden". This supposition is now proved, as 

 far as the Hieracia are concerned. 



In my opinion, Bateson is therefore right in saying that no 

 indisputable examples of non-segregating crosses have been 

 found among plants, as the Hieracium hybrids, which 

 apparently were a proof of non-segregation, have by my 

 investigations been unravelled to be constant only on 

 account of apogamy, and probably would segregate when 

 crossed back with the parents. — 



The results of our going through the literature do not seem 

 to indicate that h3'bridization is of great importance for the origin 

 of species. However, it would be too precipitate to deny its value 

 absolutely. There are many facts to indicate that it is still of some 

 consequence. Firstly, as already stated above, new constant forms 

 can arise also in segregating hybrids through segregation during several 

 generations. And secondly, we have our special case, Hieracium, where 

 the artificially produced hybrids immediately act as new species which 

 breed true from seed (on account of apogamy). In nature the same thing 

 must happen; the hybrids act quite as normally sexual species and 

 have consequently the same worth as these. However, this method 

 of the origin of species has, as already pointed out by N.XGELI and 

 Peter, the restriction, that the hybridogenous new species do not 

 bring new characters, but only now combinations of already existing 



