Non-Mendelian Inheritance 99 



It is obvious that the F, generation should all be normal 

 green and albomaculata would appear only in later 

 generations. Correns made this cross, using normal 

 green pollen and albomaculata ovules, and secured 

 results that seemed startUng. All of the individuals 

 of the F, generation were albomaculata and all the later 

 hybrid generations were albomaculata. To Correns 

 there seemed to be only one conclusion possible, and 

 that was that the pollen did not affect anything one 

 way or the other, and that inheritance was all on the 

 maternal side. When a possible mechanism to explain 

 such a phenomenon is considered it is obvious that the 

 situation cannot be explained on the basis of Mendel's 

 law. The explanation suggested by Correns is ingen- 

 ious and seems fairly reasonable. 



He suggests that the albomaculata character is due 

 to a disease of the cytoplasm which does not affect the 

 nucleus. The nuclei in these albomaculata plants are 

 supposed to carry factors for chlorophyll formation, just 

 like those of the normal green plants, but the cytoplasm 

 about the nucleus is diseased. Thus the disease is passed 

 on at cell division simply because the cytoplasm is 

 divided and passed on. In fertilization, however, no 

 cytoplasm enters the egg with the male gamete, but only 

 a nucleus; therefore it would be impossible for the dis- 

 ease to be transmitted by the pollen, and an albomaculata 

 pollen would have no effect in inheritance. The only 

 chance to transmit the disease would be through an 

 egg with diseased cytoplasm. In inheritance, there- 

 fore, the albomaculata character is handed down 

 only by the female parent, and this is maternal 

 inheritance. 



