Majichestcr Memoirs, Vol. Ivi. {\g\i-\2). 9 



red colour is due to a red sap, particularly well developed 

 in the cells on the outside of the petals. The hybrid 

 between these two species, which is often found in the 

 limestone dales in Derbyshire, presents both characters. 

 It shows a blending of other characters as well, and 

 deserves its name Ge7ini intcniicdiuni. (See PL, Figs. 3, 

 4 and 5.) 



It can be easily produced artificially, and in the 

 •second hybrid generation (/2) I have found it to produce 

 plants some of which have completely red flowers, others 

 with yellow flowers devoid of red colour, and, again, a 

 few plants with absence of both pigments, and therefore 

 presenting pure white flowers. {Pi, Fig. 6.) The throw- 

 ing off of these plants with white flowers may be due to 

 the fact that the red colour {aiitJiocyaniii) may be caused, 

 as has been shown in other cases, by two factors, which 

 must be combined in the same individual before the 

 colour is produced, or possibly it would be simpler to 

 suggest that we are dealing with two pairs of allelo- 

 morphic characters — (c?) presence of red sap and absence 

 of red sap, ib) presence of yellow plastids and absence of 

 yellow plastids. 



In this case we should obtain one plant with absence 

 of red sap and absence of yellow plastids, i.e., with white 

 flowers, out of every 16 plants in the/2 generation. Unfor- 

 tunately, the plants raised up to the present are too few 

 to give any definite numerical ratios. 



It is interesting in this connection to record the fact 

 that I have obtained plants with pure white flowers in the 

 /2 generation from the hybrids between the Primrose 

 (Primula acaulis) and the true Ox lip (Primula elatior), 

 both of which have yellow flowers. 



There has been much speculation as to w^hether the 

 sexes (male and female) represent a pair of allelomorphic 



