seedling plants of the different types bear to each other. It 

 should be added that this evidence is extremely convincing 

 to those who are really acquainted with the actual facts in- 

 volved. 



Another N'ery interesting indication of the close relation be- 

 tween these vegetable types is furnished by the fact that all 

 of them are subject to the same kinds of diseases, although in 

 different degrees. Dr. J. C. Walker (University of Wisconsin 

 and Bureau of Plant Industry) in experimental tests of re- 

 sistance to cabbage "yellows" (Jour, of Agric. Research 37 : 

 233-241, 1928) found that the wild type, together with varieties 

 of broccoli and cauliflower, were highly immune, while kohl rabi 

 and most varieties of regular cabbage were regularly susceptible, 

 although in varying degree. The point is that the wild form does 

 not differ in respect to "yellows" from the vegetable cabbage 

 types, but is like some and different from others. 



It is a fact, nonetheless, that all the principal types of this 

 cabbage tribe have been known and used for the last two thou- 

 sand years, and probably longer. Their production cannot be 

 ascribed to the work of any modern "plant wizard," to use that 

 misrepresentative and over-worked appellation of the news- 

 paper headline writer. If their original production was the 

 work of any particular horticulturists, apparently publicity 

 was not so well handled in those days. No names have come 

 down in history. 



This group of plants, therefore, illustrates a principle which 

 is often overlooked in these days of emphasis on the new dis- 

 coveries of science, important as these are. With respect to 

 these cabbage types and also with reference to most types of 

 cultivated plants and animals, it is probably safe to say that 

 at least eighty percent of the distinct and desirable varieties 

 represent old forms, selected and perpetuated since before the 

 rise of modern genetics. 



W^e believe that in the principles of Mendelian heredity, we 

 have found the key to incalculable progress in future breeding, 

 and it may well be that fifty years hence, the new kinds of 

 cultivated plants may be so extensive and revolutionary as prac- 

 tically to replace most of our current forms. However the pro- 

 gress which has been made during the last fifty years in 

 producing important changes among cultivated plants is but a 



