274 CONCLUDING KEMARKS. ChaI'. IX. 



movement is appcarently due to the drying of the under 

 surface, although this is covered with a thick layer 

 of viscid matter. The edges, however, of the saddle 

 might become slightly dry in the nine seconds. When 

 the saddle-formed disc is placed in spirits of wine it 

 contracts energetically ; and this is probably due to 

 the attraction of alcohol for water. When replaced in 

 water it opens again. Whether or not the contraction 

 is wholly hygrometric, the movements are admirably 

 regulated in each species, so that the pollen-masses, 

 when transported by insects from flower to flower, 

 assume a proper position for striking the stigmatic 

 surface. 



These various movements would be quite useless, 

 unless the pollinia were attached in a uniform position 

 to the insects which visit the flowers so as to be always 

 directed in the same manner after the movement of 

 depression ; and this necessitates that the insects should 

 be forced to visit the flowers of the same species in 

 a uniform manner. Hence I must say a few words 

 on the sepals and petals. Their primary function, no 

 doubt, is to protect the organs of fructification in the 

 bud. After the flower is fully expanded, the upper 

 sepal and two upper petals often continue the same 

 office. We cannot doubt that this protection is of 

 service, when we see in Stelis the sepals so neatly re- 

 closing and reprotecting the flower some time after its 

 expansion ; in Masdevallia the sepals are permanently 

 soldered together, with two little windows alone left 

 open ; and in the open and exposed flowers of Bol- 

 l)()phyllura, tlie mouth of the stigmatic chamber 

 after a time closes. Analogous facts with respect to 

 Malaxis, Cephalanthera, &c., could be given. But tlie 

 hood formo(l l)y the upper sepal and two upper petals, 

 besides affording protection, evidently forms a £-uide,. 



