1 68 Sex in Bryony [CH. 



by him, but the occurrence was quite exceptional. One 

 plant alone showed a distinct tendency to the monoecious 

 condition, almost resembling alba. If maleness were domi- 

 nant this prevailing absence of indications of the monoecious 

 condition is not easily accounted for. 



In view of this difficulty it is worth considering whether 

 other schemes are not equally possible, and it seems to me 

 that there is another method of interpreting the facts which 

 is certainly not yet excluded. In Correns' scheme male- 

 ness is taken to be dominant, but if femaleness is taken to 

 be dominant we can then represent the appearances thus : 



dioica $ has egg-cells $ and $. 



dioica $ has pollen all $. 



alba $ has egg-cells $ and $ ; and pollen all $. 



The matings will then stand as follows : 



A. dioica $ x dioica $ gives females $ $ and males $ $. 



B. dioica ? x alba $ gives pure females $ $ and hetero- 



zygous females $ $. 



C. alba $ x dioica $ gives females $ $ and males $ $. 



D. It follows that alba self- fertilised should give pure 

 females as well as the ordinary monoecious plants. Whether 



this is the case or not I do not know. Only three plants 

 were raised from seed here, and these were monoecious, but 

 there would be of course nothing unusual in a species, often 

 monoecious, producing female plants, for many such examples 

 are known. 



The view that it is \hefemale and not the male which is 

 heterozygous in sex is not improbable because, as will soon 

 be shown, there is a remarkable group of cases among animals 

 in which that interpretation is almost forced upon us. 



Lastly, for the apparently anomalous representation of 

 the pollen-cells of alba as of a constitution dissimilar to that 

 of the egg-cells of the same plant, we can quote (Chap, xi) 

 a somewhat parallel case which is well established in regard 

 to Stocks (Matthiola), where certain strains have the egg- 

 cells of two types and pollen-cells of one type. In that 

 case however the pollen-grains bear the recessive character, 

 not the dominant as they must be supposed to do here. 



