H. BOTANY AND HORTICULTURE. 371 



came in, and other species of similar physical peculiarities, 

 and Ireland and Southwestern England received contribu- 

 tions from the western flora of Europe. It is an interesting 

 fact that of 120 plants which are eastern as regards Great 

 Britain, only eighteen reach Ireland, and but five extend to 

 its western side. The British flora is therefore simply an ex- 

 tension of the Continental flora, with which it is no longer 

 continuous in area. There are no species in the British Isles 

 which are peculiar to them. The time which has elapsed 

 since their separation from the main-land has not been suf- 

 ficient to permit that differentiation of form which might re- 

 sult in distinctions of specific value. 



This fact is strongly in contrast with what we find in Ma- 

 deira, where the island is clothed with vegetation which is as 

 old as the miocene, and verv different from that of the nearest 

 continent. As a general rule, the species of plants shown to 

 be common to Great Britain and the Continent exhibit com- 

 paratively little difference in the Avay of definable varieties ; 

 this, however, being indicated, if at all, by the bramble and 

 dog-rose, of which the British sub-species and races are some- 

 wdiat different from those of France or Hungary. 13^4, 

 Mbruary 15, 1813, Q8. 



SENSITIYEXESS IN PLANTS A MEANS OF SECURING CEOSS- 



EERTILIZATION. 



F. E. Kitchener, in 7Vie Journal of Botany, adds another 

 to the many curious methods by which cross-fertilization is 

 secured in flowers. In the musk plant {3Iinmlus nioschatics) 

 the opened flower is horizontal, the stigma close against the 

 upper part of the throat, with two broad expanded lobes, the 

 viscid stigmatic surfaces looking downward, and two pairs 

 of unequal stamens, shorter than the style, with the anthers 

 opening downward, and in such a position as to make it im- 

 probable that any of the pollen should, without interference, 

 reach the stigma. Any insect, however, having entered and 

 covered his back or proboscis with pollen, would of necessity 

 leave a portion upon the stigma in his retreat, were not this 

 also effectually prevented by the sensitiveness of the lobes, 

 which shut closely together immediately after being touched 

 by the insect in entering. Only in case of his having previ- 

 ously visited some other flower, and bringing a contribution 



