stout: pollinations in cichorium intybus 



355 



pollen of plant Bb. This sort of combination is assumed not to 

 be possible in the previous crosses. Why the plants bG and Bb 

 cannot likewise be fertilized by their own b pollen is not clear. 



These discrepancies and assumptions of special conditions arise 

 in part from the interpretation that sterility is concerned only 

 with the interaction between the pistil, composed of diploid cells, 

 and the pollen tubes with cells of haploid constitution. Yet in 

 regard to the interaction, all of the pollen grains are treated as 

 if they were alike, although a single grain is assumed to carry only 

 one line stuff" and to transmit this in purity. 



Correns' results are excellently tabulated, but the number of 

 seed per capsule is not recorded, nor is there given a standard of 

 optimum fertility. The development of the capsules is judged 

 and graded as nichts, einsamig, sehr schlecht, schlecht, ziemlich 

 schlecht, ziemlich gut, sehr gut, and gut; or beschadigt. It is not 

 clear that capsules classified as "schlecht" always contained seed, 

 or that there is any development of completely empty pods. 

 A study of the data given, however, shows that all degrees of cross- 

 fertility and cross-sterility appeared. This may be illustrated 

 by some of the results of pollinations from plant B as recorded in 

 table I, p. 403. 



Female parent 



2 qu 



I 1 



I a 

 Ik 

 I u 



1 y 



2p 



2 ab 



No. of flowers 



5 



5 



10 



9 

 10 



13 

 10 

 12 



Results 



alle sehr gut 

 alle gut 



6 nichts, 3 ziemlich gut 



7 nichts, I gut, I schlecht 

 9 nichts, I schlecht 



12 nichts, I sehr schlecht 



alle nichts bis auf i einsamige Schote 



alle nichts 



Correns realized that such results are difficult to classify. 

 "Die Ergebnisse entsprachen nicht ganz meinen Erwartungen; 

 sie waren nicht so eindeutig scharf, wie ich gehofft hatte, und 

 zwar in doppelter Hinsicht" (p. 400), and also that there is 

 "Grossere Schwierigkeiten fiir die Beurteilung der Ergebnisse 

 bot das 'schlechte' Ansetzen; wenn z. B. in einer Schote nur einige 

 "wenige Samen oder nur einer ausgebildet wurde" (p. 401). Yet 

 Correns does not fully recognize that a feeble fertility or a partial 

 sterility may actually exist quite apart from any or all artificially 

 unfavorable conditions and errors in manipulation. The data 



