12 Colour and other Characters in the Potato 



to be heterozygous as regards sterility of anthers. No connection was 

 observed between the condition of the male and female organs. 



The presence of pollen in the anther being as we have seen a 

 recessive character, it is of some interest to note how it behaves in 

 selfed families. Unfortunately these pollen observations were not 

 begun till 1909, although the breeding experiments began in 1906. 

 Still a good deal of information may be extracted from the early notes. 



Thus, in 1906, a red-tubered seedling derived from a "Flourball" 

 plant in 1904, was "selfed," and gave rise to a large number of 

 seedlings. One white-tubered plant {D) was reserved. From this a 

 further generation was bred, and from this again another, so that in 

 this case the family has been handed through five generations, and in 

 all the anthers have had abundant pollen though the quality of the 

 pollen was bad. 



Two other lines, A and 0, derived from " Flourball," have been 

 bred through three and four generations respectively, and the recessive 

 character, viz. presence of pollen in the anther, has remained true. 



The occurrence of spontaneous sterility, due to absence of pollen, 

 has already been mentioned as having taken place in the F"^ generation 

 of the family " Congo " x " Flourball " ; it has also been observed in 

 some other families where it was unexpected, but in all these cases it 

 has occurred in normal and not deformed or strictly " contabescent " 

 anthers. It is possible that " contabescence " is not a simple character 

 but that absence of pollen and deformity of anther are due to separate 

 factors between which exists an intimate linking. 



The relations between quality and quantity of pollen and the shape 

 of pollen in varieties and species of Solanum are discussed elsewhere (9). 



Heeedity of Characters in the Haulm. 



The difficulties in relation to haulm characters have already been 

 adverted to ; although to experts constantly reviewing crops of well- 

 grown varieties it becomes comparatively easy to diagnose a variety by 

 the general appearance of the foliage, and by inspection to designate 

 at once such and such a potato as an " Up-to-Date " variety, or a 

 " Ringleader " type, and so forth, yet if one closely compares any two 

 foliages, taking corresponding specimens from various parts of the plant, 

 it will be found very difficult to describe any constant differentiating 

 character between any two varieties; there are differences no doubt, 



