78 Experime7its with Primula sinensis 



gametes of one sex only, those of the opposite sex consisting of equal 

 numbers of the four kinds (p. 128). Other cases however are apparently 

 not susceptible of complete explanation on these lines, and it seems 

 possible that they may indicate the existence of lower forms of coupling 

 than any given by the gametic series 



n-\ : 1 : 1 : w-l.» 



Further experiment however is needed before any definite opinion 

 can be expressed upon this point. 



The history of P. sinensis, since its introduction into England in 

 1820, has been given by Mr A. W. Sutton^ and further notices by other 

 writers have appeared from time to time^ It is interesting to notice 

 that the earliest illustrations^ of the species represent short-styled 

 plants of the ordinary habit (not stellata) with palmate leaves, light red 

 stems, and light magenta flowers — all dominant characters. 



Heterostylism. 



In an earlier report Mr Bateson and the writer showed that the 

 inheritance of the characters of long and short style is of a simple 

 Mendelian type, the short style being dominant®. 



All the short-styled plants originally obtained for the purpose of 

 these experiments proved to be heterozygous, but from their progeny 

 pure short-styled plants have now been obtained. Nine such plants 



^ Bateson, Saunders and Punnett, Rep. Evol. Comm. Roy. Soc. iv. 1908, p. 3. 

 Lower series would be given by the general expression 



n-x : X : X : n-x 

 where x is any odd number less than - . The expression may be made a general one, 



including all forms of partial repulsion as well as coupling, if x be taken as any number 

 less than n. The F2 series would then be given by the expression 



371^ - X (2n -x) : X (2n -x) : x (2n -x) : (n - x)^. 



^ Journ. Roy. Hort. Soc. Mar. 1891, xiii. p. 99. 



3 Gard. Chron. 1889, p. 115 ; Ibid. 1890, p. 564 ; Ibid. 1892, p. 12; Ibid. 1902, p. 269. 



* Bot. Reg. 539, May 1, 1821, under the name P. praenitens, and Lindley's Collectanea 

 Botaniea, Tab. VII, 1821. The plants figured in the two works are clearly of very similar, 

 if not identical, types. In Lindley's plate the drawings of the dissected flower apparently 

 represent the short-styled form ; the flowers shown on the plant have rather the appearance 

 of long-styled flowers. 



5 Bateson and Gregory, Roy. Soc. Proc. B, Vol. 76, 1905, pp. 581—586. 



