190 Mn. C. DAHWIX ON THE SEXrAL EEEATIONS OP 



of stamens, borne bj tlie two other forms, of corresponding lengths, 

 comes out conspicuously. In the mid-styled form the distended 

 pollen-grains from the longer stamens had nearly double the 

 diameter of those from the shorter stamens ; so that there is a 

 greater difference in this respect than in L. salicaria. In the 

 long-styled form, also, the ditforence in diameter between the 

 pollen-grains of the longer and shorter stamens was plainer than 

 in L. salicaria. These comparisons, however, must be received 

 with caution, as they were made on specimens long kept in a 

 dried condition. 



Ly thrum tJujmifolia. — This form, according to Vaucher*, is 

 dimorphic like Primula, and therefore presents only two forms. 

 I received two dried flowers from Kew, which presented two 

 forms : in the oue form the stigma projected far beyond the calyx, 

 in the other it was included within the calj's ; in this latter form 

 the style was only one-fourth of the length of the style of the 

 other form. There are ojily six stamens ; these are somewhat 

 graduated in length, and in the short-styled form the anthers 

 stand a little above the stigma, but yet the stamens by no means 

 equal in length the pistil of the long-styled form ; in the long- 

 styled form the stamens are rather shorter than in the other 

 form. Tliese six stamens alternate with the petals, and corre- 

 spond homologically with the longer stamens of L. salicaria and 

 i. Qrmfferi. As there are only six stamens, it is scarcely possible 

 that this species can be trimorphic. 



Lyihrum Tiyssopifolia. — This species is said by Vaucher, but I 

 believe erroneously, to be dimorphic. I have examined dried 

 flowers from twenty-two separate plants from various localities, 

 kindly sent to me by Mr. Hewett C. Watson, Prof. Babington, and 

 others. These were all essentially alike. Hence the species cannot 

 be dimorphic. The pistil varies somewhat in length, but when un- 

 usually long the stamens are likewise generally long ; in the bud the 

 stamens are short : perhaps these circumstances deceived Vaucher. 

 There are from six to nine stamens, graduated in length ; the sta- 

 mens which are variable in being present or absent correspond with 

 the six shorter stamens of L. salicaria and with the six which are 

 absent in Z. thymifolia. The stigma is included within the calyx, 

 and stands in the midst of the anthers, and would generally be 

 fertilized by them ; but as the stigma and anthers are upturned, 

 and as, according to Vaucher, there is a passage left in the upper 

 side of the flower to the nectary, there can hardly be a doubt that 

 * Hist. Phya. dos Hantes d'Europe, torn, ii. (1841) pp. 369, 371. 



