INTERNATIONAL CONFERENCE ON PLANT BREEDING. 421 



The other parent used was apparently a self-coloured Red (" Rohre und 

 Lippen roth, die Lippen dunkler"). The original cross, therefore, may- 

 be described as Flesh Bicolor x Red Self, and the two pairs of unit- 

 characters concerned in the mating would appear to be Red + Flesh and 

 Self + Bicolor. 



In the first generation, Flesh Bicolor x Red Self gave all Red Selfs, 

 Red being dominant over Flesh, and Self over Bicolor. In the second 

 generation the result was : 9 Red Self : 3 Flesh Self : 3 Red Bicolor : 1 

 Flesh Bicolor ; which is the simple Mendelian expectation ; the proportion 

 of Red : Flesh, and Self : Bicolor, being each 12 : 4 or 3 : 1 (the Red Bicolor 

 is, of course, the Red and White form known as Delila, while the Flesh 

 Self is that known as Flesh-coloured). In the third generation de Vries 

 found that some of the Red Bicolors and some of the Flesh Selfs bred 

 true, while others of the Flesh Selfs gave a mixture of Flesh Selfs and 

 Flesh Bicolors. Some of the Red Selfs gave a mixture of Red Selfs and 

 Flesh Selfs, while others gave a mixture of Red Selfs and Red Bicolors. 

 All these results are in accordance with the above interpretation, for the 

 expectation in the third generation would be that all the Flesh forms 

 (whether Selfs or Bicolors) would breed true to the Flesh colour, while 

 all the Bicolors (whether Red or Flesh) would breed true to the Bicolor 

 character. Similarly some of the Red forms would breed true, while 

 others would give a Mendelian mixture of Red and Flesh forms ; while 

 some of the Selfs would breed true, and others would give a Mendelian 

 mixture of Selfs and Bicolors. 



This interpretation of the facts in a simple Mendelian way has the 

 advantage of avoiding the complicated question of the resolution of com- 

 pound characters. It also explains the fact that the Flesh Self crossed 

 with the Red Bicolor (Delila) gave all Red Selfs like the original form, 

 for Red is dominant over Flesh and Self over Bicolor. 



De Vries apparently regards this as a true synthesis, and presumably 

 would expect the Red Selfs obtained in this way to breed true. 



If, however, the reviewer's interpretation be correct, these Red Selfs 

 would not breed true, but would give rise to all the four forms again. In 

 other words, the Red Selfs obtained from Flesh Self x Red Bicolor 

 would have the same gametic constitution as the Red Selfs obtained from 

 Flesh Bicolor x Red Self. The above discussion of Prof, de Vries* 

 Antirrhinums provides a good illustration of the value of the Mendelian 

 principles. No matter what interpretation may be advanced to explain 

 certain facts, its value can be at any time tested and determined by a few 

 simple experiments. 



Some Conclusions. By Max Leichtlin, of Austria. 



In this paper Herr Max Leichtlin gives some practical suggestions as- 

 to the most favourable conditions of pollination. A warm cloudy day is 

 best for six-tenths of plants, others require a dry atmosphere like their 

 native climate. Fertilisation should not be attempted before the stigma 

 is ripe, and the pollen should be neither too fresh nor over-ripe. In many 

 cases it is well to put a hand-glass over the fertilised flowers for a day 

 or two, to raise the temperature. Pollen can be kept in small glass vessels, 



