THE EVOLUTION OF LIVING BEINGS. |J lOQ 



„Brassica are descended, according to the viewa- 

 „dopted by Godron and Mezger, from two species, B. 

 „napus and B. rapa; but according to other bota- 

 „nists from three species, whilst others again strong- 

 „ly suspect that all these forms, both wild and cul- 

 „tivated ought to be ranked as a single species. 

 „Brassica napus has given rise to two large groups, 

 „namely Swedish turnips (beUeved to be of hybrid 

 „origin) ; and Colzas the seeds of which yield oil. 

 „Brassica rapa (of Koch) has also given rise to two 

 „races, namely common turnips and the oil-giving 

 „rape." 



Peas. 

 Vol. I, p. 349. ..Whether many of the new varieties 

 „which incessantly appear are due to such occasio- 

 „nal and accidental crosses I do not know." 



Beans. 

 Vol. I, p. 349. „With respect to beans (Faba vulgu- 



„ris), I will say but Httle As in the case of the 



„pea, our existing varieties were preceded during 

 „the Bronze age in Switzerland by a pecuUar and 

 „now extinct variety producing very small beans." 



Potato (Solanum tuberosum). 

 Vol. I, p. 350. „There is Uttle doubt about the paren- 

 „tage of this plant, for the cultivated varieties differ 

 „extremely little in general appearance from the wild 

 „species which can be recognized in its native land 

 „at the first glance. 



The Vine (Vitis vinifera). 

 Vol. I, p. 352. „The best authorities consider all our 

 „grapes as the descendants of one species which 



