STUDIES IN THE INHERITANCE OF 

 DOUBLENESS IN FLOWERS. 



I. PETUNIA. 



By E. R. SAUNDERS, 



Lecturer mid late Fellow, Newnham College, Cambridge. 



The tradition that the production of double flowers is largely a 

 matter of external conditions has already been shown in the case of 

 Matthiola to be at variance with the results of breeding experiments 

 carried on for several years'. The evidence, on the contrary, clearly 

 shows that in this case doubleness, like the other characters investigated, 

 is inherited according to definite laws, and in accordance with the 

 Mendelian principle of segregation". With a view to making a com- 

 parative study of the inheritance of doubleness in plants a series of 

 experiments has now been undertaken in various other genera. In the 

 case of Petunia the results have already reached a point at which 

 a definite statement can be made, and it is with these results that the 

 following account is concerned. 



' Of the many beliefs still held regarding the occurrence of doubles in Stocks, the 

 only one which I have so far been able to confirm is that seed which has been kept 

 produces a higher proportion of doubles than that more recently harvested. This appears 

 to be true to the extent that the seeds destined to give rise to doubles retain their vitality 

 rather longer than those which give rise to singles. The higher proportion observed 

 is not therefore due to any effect of age on the constitution of the seed, but to an original 

 difference in viability. 



'' A general statement of these results has already appeared, and a more detailed 

 account is now in preparation. (See Reports to the Evolution Committee, Royal Society, 

 II. p. 29, 1905 ; III. p. 44, 1906 ; iv. p. 36, 1908.) 



