278 PLANT HYBRIDIZATION BEFORE MENDEL 



In crosses involving pubescent chaff but no beards, a similar 

 set of 6 types appeared. Where one of the parents had pubescent 

 chaff of dark brown color, 12 types were theoretically possible 

 and were actually found. The remark follows : 



"it was stated above that the first generation tends to be the same in 

 similarly bred hybrids and is intermediate between the parents." (p. 89.) 



This was found to be the case in 1 1 out of 14 crosses. In a 

 case involving "velvet" (pubescent) chaff, there were 12 types 

 in the second generation, 6 with velvet, and 6 without. In the 

 first generation, 1 out of 9 plants differed from the rest only 

 in having no "velvet" or pubescence on the chaff. Such plants 

 of the first generation produced only the 6 types without "velvet" 

 in the second generation. 



A general statement, also quite remarkable in character, is made 

 to the effect that : 



"It has been stated by nearly all investigators that there is a tendency 

 in the second and later generations, to revert to the parent form. It 

 seems possible that there is a more accurate way of stating this. The 

 types that tend to occur in the second generation, as indicated by our 

 results, include all possible combinations of the characters of the two 

 parents. This of course ijicludes the parent forms themselves, and we find 

 the parent forms repeated in the second generation, constituting appar- 

 ently certain definite portions of this generation!' (Italics inserted.) 

 (p. 89.) 



Another interesting statement then follows : 



"Another important fact, that is clearly revealed by the tables of 

 percentages, is that the type that is most abundant in the second genera- 

 tion is the same as the first generation type, whether the latter is of the 

 usual intermediate type or otherwise. The exceptions to this are so rare 

 as to render them doubtful." (Italics inserted.) (p. 89.) 



So far as the writer knows, this constitutes the first and, in- 

 deed, the sole observation from the time of Kolreuter, with the 

 exception of Mendel's own investigation, to take note of the fact 

 that, in the second generation, the most abundant type to appear 

 is the type of the first generation itself. This is an observation 

 of the fact which Mendel definitely worked out, of the appearance 

 in the second generation of 2 Dr to one each of the DD and rr 

 types, the Dr type being the reappearance of the original Dr 

 combination of the first generation. 



Spillman goes on to comment upon the work of hybridization 

 done since the time of Kolreuter, having special reference to the 



