REPRODUCTIVE ORGANS IN THE PRIMULACEE. 107 
to four!* A most remarkable contrast is afforded when we com- 
pare the fertility of the form with stamens and styles of an equal 
length with that resulting from the homomorphie unions ; thus, 
taking the long-styled as the more fertile of the homomorphie 
unions, we see that the average excess of seeds per capsule in 
favour of the former is eighteen, affording the proportions of two 
to one! In the four reciprocal unions of the long- and short- 
styled forms with the non-dimorphic form, the results are remark- 
ably complicated. Thus, the non-dimorphie form by pollen of 
the long-styled form yields an average of seven seeds per capsule; 
and by the converse union, 7. e. pollen of the former applied to 
the stigma of the latter form, the average of seeds per capsule 
is reduced to five, or as four to three. Again, the non-dimorphic 
form by pollen of the short-styled form yields an average of nine 
seeds per capsule, whereas from the converse union the average 
is only four seeds per capsule—that is, as two to one! In 
these illustrations we clearly see that a complete derangement 
of the normal dimorphie relations of the two forms in their con- 
verse unions has been effected ; thus the short-styled form used 
as female with the non-dimorphie form yields the lowest grade of 
fertility—four seeds per capsule, whereas used as male with the 
non-dimorphie form the highest grade of fertility is afforded—nine 
seeds per capsule! It is also worthy of notice that the non-di- 
morphic in both unions as female, with the long- and short-styled 
forms, exceeds in fertility the converse unions in about the pro- 
portion of two to one! The fertility of all these cross-unions, 
relatively to the pure unions of the long- and short-styled forms, 
is greatly decreased. Thus the united short-styled pure homomor- 
phic and heteromorphic unions yield more seed, in about the pro- 
portion of three to one, than those from the united cross-unions of 
the long-styled and non-dimorphie form! Again, we find a great 
increase in the proportions by making a similar comparison of 
the pure long-styled homomorphic and heteromorphic unions with 
the cross-unions of the long-styled and non-dimorphic form, the 
average in this case being as five to one! 
We thus see that the above Cowslip, structurally characterized, 
as I have previously stated, by an equality in the length of the 
stamens and styles, and in the resemblance of the pollen-grains 
and stigmas to those respectively characteristic of the long- and 
* Mr. Darwin informs me those individuals of the P. Sinensis which have 
stamens and styles of an equal length are also more fertile with own pollen 
than a heteromorphie union ! 
LINN. PROC. —BOTANY,. VOL. VIII K 
