82 



MB. C. DARWIN 0>- THE DIMOIiPHIC CO'DITIOS 



vationa in detail, tlioiigh I am far from supposing that all cases of 

 dimorphism are alike. The first idea which naturally occurred 

 was, that the species were tending towards a dioicous condition ; 

 tliat the long-styled plants, with their rougher stigmas, were more 

 feminine in nature, and would produce more seed ; that the short- 

 styled plants, with their long stamens and larger pollen-grains, 

 were more masculine in nature. Accordingly, in 1860, I marked 

 some Cowslips of both forms growing in my garden, and others 

 growing in an open field, and others in a shady wood, and gathered 

 and weighed the seed. In each of these little lota the short-styled 

 plants yielded, contrary to my expectation, most seed. Taking 

 the lots together, the following is the result : — 





No. of 

 Plants. 



No. of 1^0. of 

 Umbels Capsules 

 produced, produced. 



WJight of 

 seed in 

 grains. 



Slioi-t-styled Cowslips 

 Long-styled Cowslips 



9 

 13 



33 199 

 51 201 



83 

 91 



If we reduce these elements for comparison to similar terms, ' 

 have — 





No. of 

 Plants. 



Weight 



of seed in 



grains. 



No. of ^«ft 

 U-l"^''- seed. 



No. ot 

 Capsules. 



Weight 



of seed in 



grains. 



Short-styled Cowslips 

 Long-styled Cowslips 



10 

 10 



92 

 70 



100 

 100 



251 



178 



100 



.100 



41 i 



34 ; 



So that, by all the standards of comparison, the short-styled are 

 the most fertile ; if we take the number of umbels (which is the 

 fairest standard, for large and small plants are thus equalized), the 

 short-styled plants produce more seed than the long-styled, in the 

 proportion of four to three. 



In 1861 I tried the result in a fuller and fairer manner. I 

 transplanted in the previous autumn a number of wild plants 

 into a large bed in my garden, treating them all alike ; tlie result 



Short-styled Cowslips . 

 Long-styled Cowslips , 



No. of I No. of 

 Plants, j Umbels. 



47 



58 



I Weight of 

 seed in 

 grains. 



173 

 208 



745 

 692 



