MONOGRAPH OF THE BRITISH SPECIES OF EUPHRASIA. 325 



throat and lower lip being usually furnished with a yellow spot, which 

 doubtless acts, as do the three darker-coloured nerves of the divisions, 

 as a guide to visiting insects. The outer surface of the upper lip is 

 always furnished with fine-jointed, many-celled hairs extending to 

 the tube, where the hairs are stronger and decurved. The lower lip 

 is also usually provided with similar hairs, together with a few 

 shortly stalked glandular ones. The tube is internally furnished 

 with stronger one-celled hairs curved at their tips ; they doubtless 

 serve to prevent the intrusion of undesirable insect visitors, who 

 would steal the honey without assisting in cross-fertilization. The 

 hairs of the corolla offer no valuable specific characters. 



In some species the corolla-tube lengthens considerably after the 

 opening of the flower ; this growth and the size of the corolla as a 

 whole afford valuable specific characters. 



The Stamens are always four in number ; the anthers are 

 situated under the hood of the corolla ; the filaments are inserted 

 in the throat of the corolla ; they are curved outwards. The two 

 anterior stamens are longer than the posterior ; the anther- cells are 

 distinct and parallel, the anterior ones are spurred in all the 

 British species. 



The Style and Stigma. — The style is long and fihform, and 

 arises from the apex of the ovary ; at the time of flowering it is 

 bent or curved under the hood of the corolla. The stigma is small, 

 disk-like, undivided, and papillose. 



Fertilization. — In the section (TrandijJorcE, the flowers are 

 proterogynous, the style is straight from the bend under the hood 

 to the apex and projects beyond the upper lip even before the 

 flower has perfectly expanded ; the dehiscence of the anthers has 

 not yet taken place, so that cross-fertilization (zenogamy) is en- 

 sured. By the time the tube of the corolla has lengthened and 

 brought the stigma nearer to the anthers, the former has become 

 withered and discoloured. In the section Purvijiora some species 

 with intermediate-sized flowers have a similar provision to that in 

 the Giandifior(£, but other species, also with intermediate-sized 

 flowers, have the style curved under the hood and over the anthers, 

 and from that downwards so as to bring the stigma in front of the 

 former. The flowers in both are proterogynous, so that cross- 

 fertilization can take place in an early stage, but as these flowers, 

 being smaller, are less attractive to insects, the anthers dehisce earlier 

 than in the Grawlijiora, and the papilhe of the stigma have not become 

 withered, but are still capable of fertilization from contact with the 

 anthers of its own flower if zenogamy has not taken place. ' In 

 the smaller-flowered species, as in E.f/racilis and E. SalitihiDyensis, the 

 stigma is ripe for fertilization at the time of authesis, but the anthers 

 open at the same time, the style is curved at the end so as to bring 

 the stigma immediately over and in contact with the anthers, so 

 that autogamy is insured, though zenogamy is not necessarily 

 excluded. Prof. Wettstein remarks that these small-flowered species 

 occur in northern regions and in the Alps, localities in which insect 

 life is less abundant, and the flowers being less conspicuous and 



