Cbap. VII. GYKO-DICECIOUS PLANTS. 301 



maphrodites must greatly exceed in number the 

 females, at least in the localities examined by me. 

 A very dry station apparently favours the presence 

 of the female form. With some of the other above- 

 named Labiatse the nature of the soil or climate 

 likewise seems to determine the presence of one or 

 both forms ; thus with Nepeta glechoma, Mr. Hart found 

 in 1873 that all the plants which he examined near 

 Kilkenny in Iwjland were females ; whilst all near 

 Bath were hermaphrodites, and near Hertford both 

 forms were present, but with a preponderance of her- 

 maphrodites.* It would, however, be a mistake to 

 suppose that the nature of the conditions determines 

 the form independently of inheritance ; for I sowed 

 in the same small bed seeds of T. serpyllvm, gathered 

 at Torquay from the female alone, and these produced 

 an abundance of both forms. There is every reason 

 to believe, from large patches consisting of the same 

 form, that the same individual plant, however much 

 it may spread, always retains the same form. In two 

 distant gardens I found masses of the lemon-thyme 

 {T. citriodorus, a var. of T. serpyUvm), which I was 

 informed had grown there during many years, and 

 every flower was female. 



With respect to the fertility of the two forms, I 

 marked at Torquay a large hermaphrodite and a large 

 female plant of nearly equal sizes, and when the seeds 

 were ripe I gathered all the heads. The two heaps 

 were of very nearly equal bulk ; but the heads from 

 the female plant numbered 160, and their seeds 

 weighed 8 • 7 grains ; whilst those from the her- 

 maphrodite plant numbered 200, and their seeds 

 weighed only 4 ■ 9 grains ; so that the seeds from the 



'Nature,' June 1873, p. 162. 



